Welcome

The non-profit, Friends of Mineralogy (FM), a national organization founded in 1970, includes nearly a dozen chapters from coast to coast, whose members share a common love of minerals. FM’a objective is to promote, support, protect, and expand the collecting of mineral specimens, while furthering the recognition of the scientific, economic, and aesthetic value of minerals and mineral collecting. Membership includes collectors, museum curators, mineralogists, and earth science educators.  The organization is affiliated with Mindat.org, the Mineralogical Society of America (MSA), and the Mineralogical Association of Canada (MAC).

Among its many activities, FM regional chapters sponsor symposiums, and collecting trips to quarries, mine dumps, and mines across the country.  FM has made its voice heard whenever proposals are made to close mineral museums or collecting sites.  National FM co-sponsors symposiums held annually at the Tucson Gem & Mineral Show, and contributes support and speakers to other mineral symposiums.  FM presents annual awards for best article published in each of the following publications: The Mineralogical RecordRocks & MineralsMineral News, and Mineral Monographs.  It also gives awards to the best institutional and individual educational exhibit cases displayed at the Denver and Tucson gem and mineral shows.


Please send tax-deductible donations to support Friends of Mineralogy, a non-profit 501(c)3 organization, in care of Bruce W. Bridenbecker, Treasurer, 7528 Lucerne Vista Ave, Yucca Valley, CA 92284, made out to Friends of Mineralogy.

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  • by friendsofmineralogy 2 days ago
    What's left to say about "fool's gold"? The brassy shine of pyrite cubes fascinate many people new (and not-so-new) to minerals. Pyrite (iron sulfide) is one of the most common minerals, found in almost all classes of rocks. It is frequently found in metal ores, is common in coal, and can form concretions in sedimentary rocks. Pyrite usually forms cubes, but can also involve octahedrons and even 'pyritohedrons,' twelve-sided shapes with five sided faces very similar to dodecahedrons. Pyrite even replaces fossils under the right conditions. The name "pyrite" is derived from the Greek meaning "stone or mineral which strikes fire" and can indeed spark when struck against steel. The first self-igniting firearms in the 16th century used a piece of pyrite that was struck against a circular file to generate the sparks needed to ignite the gunpowder. Handy in an emergency kit? Beyond the color of the metallic shine, pyrite isn't much like gold at all. It is harder, is brittle rather than malleable, forms in defined crystal shapes instead of irregular shapes, and takes a different tone of yellow color. But — plot twist! It turns out pyrite can contain "invisible gold" hosted in nanoscale dislocations of atoms within the crystal lattice. These dislocations are 100,000 times smaller than the width of a human hair, but can add up to quantities of gold that are economically interesting. Geologist Denis Fougerouse published an article in June 2021 that reported a method of recovering nanothreads of gold from pyrite using a technique called selective leaching, a possibly more eco-friendly method of extraction than the standard method that uses energy-hungry pressure oxidizing techniques. : Jessica Robertson: Specimens from Spain; Colorado; Washington State; Elba, Italy; Huanzala, Peru; Washington State; and a pyritized ammonite. ICYMI: Each  #mineralmonday  we present a mineral species with some history and science, following along the order presented in Frederick Pough's definitive Field Guide to Rocks and Minerals; currently working through the sulfides!  #pyrite   #foolsgold   #crystalsofinstagram   #history   #minerals   #mineralogy   #crystals   #geologyrocks   #mineralcollecting 
  • by friendsofmineralogy 6 days ago
    Looking for another good mineral read? Get your hands on a copy of Paul Desautel's The Mineral Kingdom, a 1968 "coffee table" book with lavish photographs and fascinating, readable stories about the science of mineralogy, famous localities, and approaches to collecting. Although this book is long out of print, it was a successful book for general audiences and used copies remain plentiful and affordable. Paul Desautels (1920-1991) was a long time highly respected figure in the mineral community, and was Curator of Gems and Minerals in the Department of Mineral Sciences of the Smithsonian National Museum of Natural History for 25 years. He was a popular lecturer and author of several books and dozens of articles and had a major influence on public perception of minerals and mineral collecting. Thirty years after his death, his legacy remains apparent throughout the community, including the "Desautels trophy," awarded by the Tucson Gem and Mineral Society to the single best case in each year's mineral competition. The Mineral Kingdom was the first of Desautels' popular books, and while collecting styles and science may have evolved since its publication, it remains an excellent and readable introduction to the science and hobby of minerals and mineral collecting.  #minerals   #mineralcollecting   #science   #geologyrocks   #bookrecommendations   #books   #crystals   #history 
  • by friendsofmineralogy 1 week ago
    Bismuthinite (bismuth sulfide) is structurally and visually similar to stibnite, but is more uncommon and forms in different environments. Bismuthinite is a main ore of bismuth, however, bismuth is more commonly obtained as a byproduct of extraction of other metals. For a long time, bismuth was considered a form of lead. It wasn't until the mid-1700s that it was determined to be its own distinct element. Because bismuth has unusually low toxicity for a heavy metal, it's been in increasing use as a swap for the more toxic lead. At some point in your life, you've probably used Pepto-Bismol or a related cure for an upset stomach. The generic active ingredient in these elixirs is bismuth subsalicylate. One of the common side effects of these cures is a black-colored stool. That black is produced from the recombination of the bismuth subsalicylate with sulfur in your digestive system to form bismuth sulfide-- aka bismuthinite! It's temporary and harmless, but kind of neat to know your body can make minerals. : Fabre Minerals. Bismuthinite cluster from Farallón Mine, Farallón Viejo vein, Cerro Tazna, Atocha-Quechisla District, Nor Chichas Province, Potosí Department, Bolivia ICYMI: Each  #mineralmonday  we present a mineral species with some history and science, following along the order presented in Frederick Pough's definitive Field Guide to Rocks and Minerals; currently working through the sulfides!  #bismuthite   #bismuth   #history   #minerals   #mineralogy   #crystals   #geologyrocks   #mineralcollecting 
  • by friendsofmineralogy 2 weeks ago
    Ice is a mineral? Yup! Ice meets all the requirements to be a mineral: "a naturally occurring, homogeneous solid, inorganically formed, with a definite chemical composition and an ordered atomic arrangement." Well--one small caveat here, because by that definition, ice in your freezer isn't technically a mineral since it isn't naturally occurring. Moving on... On the surface of the earth ice most always crystallizes in the hexagonal system, hence why we have lovely six-sided snowflakes. However, ice can form in 19 different crystalline phases under different pressures and temperatures. In outer space, amorphous ice is the most common. Our familiar ice is really an amazing substance. It's very soft (just 1.5 on the Mohs scale) but less dense than liquid water and expands as it freezes. This means that ice floats--it is theorized that if it didn't, and instead sank below the liquid water, all bodies of water would freeze totally solid. How different would the physics and evolution of our earth be if that was so? We humans might not be here at all. The biggest problem we see with wonderous ice crystals is that they are a bit hard to ship and display. Alas. Obvious follow up question: if ice is a mineral, is a glacier a type of rock? (Yes! Debate in the comments.)  #ice   #snow   #water   #crystals   #minerals   #mineralogy   #science   #geologyrocks 
  • by friendsofmineralogy 2 weeks ago
    Large clusters of stibnite (antimony trisulfide) might resemble the Iron Throne from Game of Thrones, but the stuff is far too soft for furniture (Mohs scale 2). It's still been the stuff of drama for millenia. Back in 3,000 BCE, stibnite powders mixed with animal fat were the original cosmetic known as kohl, used for lining eyes and darkening brows. Stibnite is the main ore of antimony. So associated with antimony was it that the old latin name for antimony was "stibium." (That's why the chemical symbol for antimony is Sb.) While the best stibnite crystals are long, striated prisms, occaisionally you will see one that appears bent, like the small one on the left side of the cluster in our photo. This bend is not because the crystal broke and 're-healed,' in the way you might hear about quartz. It likely actually grew in that bent position, because stibnite's molecules gather in an unusual arrangement of a lattice of pyramids of atoms joined by weak metallic bonds. The weak bonds form a lengthwise planes of perfect cleavage, which can become 'gliding' planes, along which stibnite crystals can bend or curve as stress is applied during growth. Cluster of fine elongated stibnite crystals from La Salvadora mine, Oruro, Bolivia. 6.1 cm x 1.3 cm. Jessica Robertson photo. ICYMI: Each  #mineralmonday  we present a mineral species with some history and science, following along the order presented in Frederick Pough's definitive Field Guide to Rocks and Minerals; currently working through the sulfides!  #stibnite   #antimony   #history   #minerals   #mineralogy   #crystals   #geologyrocks   #mineralcollecting 
  • by friendsofmineralogy 3 weeks ago
    Happy New Year! Our background image is a "chrysanthemum stone" from Liuyang County, Hunan Province, China. These flower-like shapes are radial collections of celestine (some replaced by calcite and/or chalcedony) within limestone bedrock. This example, like many sold for market, is highlighted by selective painting of the matrix with a dye to enhance the crystal pattern. If you look closely within the light colored 'petals' you can see shadowy shapes of the actual crystals within the rock. This "Stone of Good Fortune" seems appropriate nevertheless. Happy New Year from Friends of Mineralogy!  #chrysanthemum   #celestine   #celestite   #happynewyear   #minerals   #mineralogy   #mineralcollecting   #geologyrocks   #geology   #chrysanthemumstone 
  • by friendsofmineralogy 3 weeks ago
    In conjunction with the Mineralogical Society of America and the Tucson Gem & Mineral Society, Friends of Mineralogy is pleased to announce the return of the annual Tucson Mineral Symposium for its 40th year! 2022 Tucson Mineral Symposium Minerals of the Apatite Supergroup and Mineral Fluorescence Saturday, February 12, 2022 Tucson Convention Center, Tucson, AZ https://www.friendsofmineralogy.org/2022-tucson-mineral-symposium/ The Tucson Mineral Symposium will be held as a hybrid event, both in person at the Tucson Convention Center and online via Zoom. Attendance in either format is FREE. In person attendance does not require registration. To receive the link to attend the online portion, please register here: shorturl.at/lpzKQ. Donations to offset the cost of the symposium can be made on the Friends of Mineralogy National website. A downloadable PDF version of the abstract book is available online. Printed copies of abstract books will be $12. You can reserve and pay for your copy on the FM website listed above. Physical copies must be picked up at the in person event in Tucson; no copies will be mailed. Additional copies will be available at the in person event while supplies last.  #minerals   #mineralspecimens   #symposium   #mineralsymposium   #tucsonarizona   #tucsongemshow   #tucsonmineralshow   #mineralsofig   #mineralcollector   #crystals   #crystallove   #crystalsofig   #mineralogy   #geology   #geoscience   #stemeducation   #earthscience   #rocksandminerals   #freeevent   #ilikerocks   #amazingnature   #mineralsofinstagram   #crystalsofinstagram 
  • by friendsofmineralogy 3 weeks ago
    The wonders of King Tutankhamun's tomb included dazzling gold ornaments and fantastic preservation. Included among those famed artifacts were containers of pigments for use in the next life and the raw materials for more, including pieces of a bright yellow crystalline material with pearly luster... orpiment! Named from the latin for gold (aurum) and pigment (pigmentum), orpiment is an arsenic sulfide closely related to and often occuring with realgar, featured last week. Like realgar, it has been widely used for pigments for millenia, and the toxicity was considered an asset in some early medicines. In the fifth century BC, Hippocrates decribed the use of orpiment in a caustic mixture to burn off skin ulcers and cancers. This would have been incredibly painful and would have caused sores, scabs, and sloughing of the damaged tissue. If used in high enough amounts for arsenic to absorb through delicate damaged tissue, this could result in a very painful death. While arsenic is widely known as this historical "poison of kings," that arsenic poison is usually arsenic trioxide, also known as "white arsenic." It does not appear that orpiment itself was ever widely used as a poison on its own, since the bright color alone would be a bit of a warning. Orpiment largely fell out of use as a pigment as chrome yellows and dye-based pigments came on the scene in the 1800s. In some places in the world orpiment is still used for removal of hair from both hides and humans, but in more modern technology it is also used for infrared-transmitting glass, photoresists, and in the treatment of certain types of acute leukemia. Photo: Jessica Robertson ICYMI: Each  #mineralmonday  we present a mineral species with some history and science, following along the order presented in Frederick Pough's definitive Field Guide to Rocks and Minerals; currently working through the sulfides!  #orpiment   #arsenic   #history   #minerals   #crystals   #geologyrocks   #mineralcollecting 
  • by friendsofmineralogy 4 weeks ago
    Naughty, or nice? Coal in your stocking, or toys and treats? A rock collector might find a nice anthracite specimen quite a treat, but placing that aside: where did this legend come from? And where does Santa get his coal? Of course, Santa lives at the North Pole, the surface of which is the snow and ice of our frozen northern sea. Not so many rocks there. He is a busy man, though, and must send his elves not too far away. The northernmost arctic coal mines in the world are on Norway's Svalbard archipelago, and have been mined since at least the early 1900s. While most of these mines have closed in recent decades, one (Mine 7) remains open, but not for too much longer: it is scheduled to close in 2023. Mine 7's primary contract was with a coal-fired power plant for communities on Svalbard, however, Svalbard plans to transition to a renewable power supply. This may mean that Santa will also have to adjust, but perhaps he has started to do so already, since when was they last time you recieved coal in your stocking? Besides, Santa did not always hand out coal. Coal isn't mentioned in "A Visit from St. Nicholas" from 1823. In the similar 1821 poem "Old Santeclaus with Much Delight," Santa gave out black birch rods as punishment. This was probably because coal wasn't widely adopted for household use, yet. The conversion from wood heat to coal occurred generally between the 1820s and 1870s. By an 1982 story “Christmas Every Day,” parents get stockings filled "pieces of coal wrapped up in tissue paper" as a sort of gag gift. As coal became common and plentiful, it became something that made it bad gift, like the switches had been 50 years before. If you have been given coal in recent years, it was probably intended as a gag or a bit of nostalgia, because now that coal has largely faded out of home use, finding coal in a stocking is a remnant of a bygone era. Santa is too kind to have kept up with the 'punishment' end of the legend, anyway. So, Friends of Mineralogy wishes you as much coal as you desire. Merry Christmas and Happy Holidays!  #christmas   #coal   #history   #geology   #mineralogy   #stem   #resources   #santa 
  • by friendsofmineralogy 4 weeks ago
    "Ruby of arsenic": Realgar! Realgar (arsenic sulfide) is gemmy red and indeed a stunning ruby-like color when fresh. Unfortunately, it can also be a 'tricky keeper' for a collector, because is also soft (Mohs 1.5-2) and will turn to powdery yellow pararealgar if stored in the light. And collectors need not worry about this part so much (just wash your hands) but of course, it's also toxic. It was used as a paint pigment for millennia, and as a rat poison in at least medieval Spain and Elizabethan England: "it kylleth rattes" according to an 18th century dictionary. (Ed. note: maybe don't paint with your rat poisons, athough this will be a recurring theme over this period that we cover the sulfides.) This quite small cluster (~ 1cm across) is a small specimen from the Green River Gorge in King County, Washington, USA. It is still a lovely red because it was stored in a small box for decades, but it also is a little roughed up at the edges because it was loose in that small box for decades. In some parts of King County and the surrounding area, concentrations of arsenic in site soil and groundwater will be found slightly above the state cleanup limits, even at sites when no human sources of contamination have been identified. This sort of deposit is why; arsenic is naturally occurring in some native rocks, and erosion by rivers and glaciers has spread it widely over the region, elevating background arsenic concentrations in some locations. Photo: Jessica Robertson ICYMI: Each  #mineralmonday  we present a mineral species with some history and science, following along the order presented in Frederick Pough's definitive Field Guide to Rocks and Minerals; currently working through the sulfides!  #realgar   #arsenic   #history   #minerals   #crystals   #geologyrocks   #mineralcollecting 
  • by friendsofmineralogy 1 month ago
    The happy twinkle of colored lights on a dark evening...what could be more festive! What makes your holiday tree sparkle? In recent years, many people have converted to strings of LED lights from the old incandescent style for efficiency and ease of use. In both types of light strings, the wire that carries all the lights is usually copper, however, the two types of bulbs work differently. Whereas the old incandescent bulbs used thermal radiation (the emission of light as a result of being heated), LED bulbs work differently. LED bulbs emit light using electroluminescence-- photons released when electricity is passed through a semiconducting diode. A semiconducting diode is a tiny little precious wonder. The color of the light produced by an LED correspondes to the energy of the photons being released, and is determined by how much energy is required for the electrons to cross the semiconductor. Using different semiconductor materials can produce different colors of light. In general, the materials used in these semiconductors include aluminum, gallium, and indium. Different specific compounds of these elements and tweaks in semiconductor construction will produce orange, green, violet, and much more! Gallium and indium are both elements that only very rarely produce their own minerals. Indium is obtained as a byproduct of processing other ores, particularly sphalerite (zinc-iron sufide). Gallium can also be obtained as a byproduct of sphalerite processing, but is more often a byproduct of bauxite ore, the main ore of aluminium, which is also key to these semiconductor compounds. The tiny semiconductors often have itty-bitty gold bonding wires, too. Gold, gallium, and indium are all metals much more abundant in the universe than here on the surface of the earth. Gallium and indium are formed during the explosions of massive stars, and gold is thought to be formed when neutron stars collide! Imagine that. Tiny pieces of star, twinkling like a clear night sky, for you to enjoy, you absolute star. FM graphic: Erin Delventhal  #science   #elements   #geologyrocks   #holidaylights   #minerals   #star   #resources   #stem   #rocks   #nature   #mineralogy   #earthscience 
  • by friendsofmineralogy 1 month ago
    Cinnabar (HgS) has been mined worldwide for millenia. The brilliant reds of an opulent Roman wall fresco, dynastic Chinese lacquerware, in Mayan royal burial chambers, and the vermillion robes in a Vermeer painting are all derived from cinnabar. Wall paintings at Çatalhöyük in Turkey (7000-8000 BC) even used cinnabar pigments! Crushed cinnabar ore can be roasted in rotary furnaces to produce liquid mercury (quicksilver). During this process, sulfur separates and evaporates, leaving pure mercury behind. Similar methods were used by the Romans and in ancient Peru. The health hazard of mercury was known back to those days; the ancient Romans considered overexposure to mercury a occupational disease. Nevertheless, cinnabar and mercury were also sometimes considered to have healing or magical properies. Ninth century Chinese Emperor Xuānzong of Tang was prescribed "cinnabar that had been treated and subdued by fire" to achieve immortality. Although he showed signs of what we now recognize as mercury poisoning, including swelling and muscle weakness, imperial alchemists consulted medical texts that listed these symptoms as evidence that the cinnabar treatment was working and dismissed concerns that the treatment was damaging the emperor's health and sanity. Emperor Xuānzong became increasingy paranoid and irritable, and died of the likely poisoning in 859. Although cinnabar pigments are replaced by less toxic alternatives today, cinnabar remains the the most common ore for elemental mercury. Today, more sophisticated furnaces and retorts are used to more efficiently recover mercury using modern precautions for use and handling. Photo: JJ Harrison ICYMI: Each  #mineralmonday  we present a mineral species with some history and science, following along the order presented in Frederick Pough's definitive Field Guide to Rocks and Minerals; currently working through the sulfides!  #cinnabar   #mercury   #history   #minerals   #crystals   #geologyrocks   #mineralcollecting 
  • by friendsofmineralogy 1 month ago
    Looking for a simple and inexpensive family activity that combines the holiday season and mineralogy? Try making borax crystal ornaments! Borax is sodium borate, a mineral found in deposits produced by the repeated evaporation of seasonal lakes. It's a useful mineral, widely used as a laundry booster, a pH buffer, and even to extract gold in small-scale gold mining! In this activity, we will be dissolving powdered borax into a saturated solution, which will then cool to crystallize into new clusters of crystals large enough to sparkle on a tree. These sparkly stunners are great for families and anyone who likes to watch crystals grow. You may even have all the materials already in your home! Parents should assist with the stove and hot water and make sure all hands are washed after handling borax. Supplies: Pipe cleaners String, fishing line, or thin ribbon Borax (sold in the laundry section of the supermarket, often as "20 Mule Team" brand) Water Stove and pot Pencils or thin sticks Mason jars or similar glass containers 1. Make ornament shapes out of pipe cleaners. If you want colorful ornaments, use colorful pipe cleaners! Shapes need to fit comfortably inside a mason jar or similar container. 2. Tie string to the pipe cleaners. 3. Dissolve borax in 3-4 cups of boiling water. Use 3-4 tablespoons of borax per cup of water. Borax should be completely dissolved so that the water is clear. 4. Pour the borax water into the jars. Suspend the pipe cleaner shapes in the jars so that they are completely submerged and not touching the sides or bottom of the jar. 5. Set the jars aside to sit for 12-24 hours. Crystals will start to grow within the first few hours. The longer the jar sits, the larger the crystals will grow! 6. Remove the ornaments from the jars and dry them off. Enjoy!  #crystals   #holiday   #crafts   #crafting   #minerals   #mineralogy   #science   #christmas   #christmasdecor   #ornaments 
  • by friendsofmineralogy 1 month ago
    National Miners Day, December 6. Miners Day was established in 2009 to commemorate the nation's worst mining disaster which occurred in the community of Monongah, West Virginia on December 6, 1907, the hundreds of miners lost that day, and to show appreciation for the sacrifices and accomplishments of all hard working mining individuals. Mining has historically been one of the most dangerous jobs. Conditions improved over time in the USA thanks to many organizers and battles over many years. In 1910, Congress created the Bureau of Mines, the precursor of the NIOSH Mining Program, to conduct research in methods to make mining safer. Because research is not enough to protect lives, additional hard political and advocacy work was required to pass The Coal Mine Health and Safety Act of 1969 and the Federal Mine Safety and Health Act of 1977, created to oversee the health and safety of all miners. The miner pictured in this 1974 photograph had just finished his shift at a coal mine near Richlands, Virginia. The equipment he wears is evidence of some of the health and safety protections that miners use, including his yellow hard hat that indicates he is a safety supervisor. His name and blood type is engraved on the brass plate on his belt, which also holds his life saver breathing apparatus and extra batteries for his headlamp. He also carries on his right hip a device to detect low-oxygen areas. The empty lunch pail carries much significance to mineral collectors - although it was a forbidden practice at many mines, occasionally miners would smuggle special mineral specimens home in just such a pail. We honor all men and women miners who have risked illness and injury in this essential industry in order to mine products that help supply the raw materials for items we all use daily.  #mining   #minersday   #minerals 
  • by friendsofmineralogy 2 months ago
    How did a man who never visited America get his name on the U.S.A.'s greatest museum? James Smithson was an English mineralogist. He was an illegitimate son of a duke, born around 1865. Wealthy from his mother's estate, he grew his inheritance into a fortune through shrewd investments, and traveled extensively through Europe studying his eclectic interests that ranged from the chemistry of snake venom to calamine. Calamine was eventually renamed "Smithsonite" in his honor. He published 27 papers in his lifetime and was a member of the Royal Society of London and rubbed elbows with Joseph Priestley and Antoine Lavoisier, among others. He was in Paris during the French Revolution, and was a prisoner of war during the Napoleonic wars - twice! He died in 1829, never having married or having any children. He left his fortune to his nephew. So how did that turn into the Smithsonian Institution? Well, he left a stipulation in his will that if his nephew died unwed and without heirs, "...I then bequeath the whole of my property [...] to the United States of America, to found at Washington, under the name of the Smithsonian Institution, an establishment for the increase & diffusion of knowledge among men." His nephew did indeed die a few years later without a wife or heirs. In 1838, the fortune (as eleven crates containing 104,960 gold sovereigns) as well as Smithson's personal items, scientific notes, minerals, and library, were brought to the U.S.A. The museum was established in 1947. So why did Smithson bequeath his fortune to the U.S.A., and not, say, the Royal Society? According to some historians: spite. Maybe it was the stigma of being an illegitimate son of nobility, or perhaps it also that he was genuinely inspired by the young nation and the progressive society that inspired the French Revolution. Sadly, we can't be certain, because Smithson's papers were destroyed in an 1865 fire that also destroyed his mineral collection. Luckily, his book collection remains intact, just like his legacy of curiosity and support of science and culture.  #smithsonian   #smithsonite   #minerals   #history   #mineralcollecting   #geologyrocks 
  • by friendsofmineralogy 2 months ago
    Often an iridescent metallic blue and purple, covellite (CuS) is a favorite of many mineral collectors. It was named for Niccolo Covelli, an Italian mineralogist and the discoverer of this mineral at Mount Vesuvius. It is a secondary minerals and often forms in association with copper deposits, but is not a widespread ore in itself. In the USA, many of the best covellite specimens were found in the mines of Butte, Montana, like our pictured specimen. Neato fun fact: covellite was the first identified naturally occurring superconductor! In a 2006 study published in the European Journal of Mineralogy, superconducting states were achieved on covellite samples from both Butte and Calabona, Italy. Covellite's crystal structure is uniquely layered and has electron excess due to isolated covalent S-2 planes. This type of research has applications in solar electric devices, lithium battery cathodes, and more. Photo: Rob Lavinsky & irocks.com ICYMI: Each  #mineralmonday  we present a mineral species with some history and science, following along the order presented in Frederick Pough's definitive Field Guide to Rocks and Minerals; currently working through the sulfides!  #sulfides   #covellite   #minerals   #crystals   #geologyrocks   #mineralogy 
  • by friendsofmineralogy 2 months ago
    Black Friday - that traditional day of mass shopping following Thanksgiving Day in the U.S.A. - involves a web of processes and technologies that depend on geology. But let’s look at just one big piece that makes the whole thing work: the credit card. Ever wonder what is actually inside these ubiquitous little marvels of technology? The body of the card is a plastic laminate, with name and number details mechanically imprinted. Lamination increases durability and allows for a wide variety of designs and coatings. The first credit cards, without the whiz-bang technology they all have now, used carbon paper copies in manual mechanical imprinting machines at the point of sale. These are still around for use when more analog methods are needed. The next big innovation in credit card technology was the magnetic strip used when you "swipe" your card. The strip is a magnetic tape laminated to the card and embedded with iron oxides derived from minerals like hematite that can be magnetically coded with the card information. While many cards still retain the magnetic strip for backwards compatibility, they are being phased out in favor of EMV chip technology. Chip cards have sophisticated microprocessors that are much more capable and secure. The chips start as boules of almost pure silicon derived from quartz sands, cut thinly and carefully to chip size. Because silicon on its own in nonconductive at room temperature, small quantities of specific "donor" atoms are added, such as boron and phosphorus, obtained from minerals like borax and phosphate rock. These donor atoms supply electrons that can then move through the silicon crystal lattice and make a semiconductive material. Transistors are built onto the doped layers of the chip. Conductive contact pads made of precious metals like gold and silver are arrayed on top. Many of the newest cards also have tiny antennae to enable contactless transactions. All of this is constructed on microscopic scales in sophisticated clean rooms.  #science   #blackfriday   #minerals   #geologyrocks   #resources   #technology  FM graphic: Erin Delventhal
  • by friendsofmineralogy 2 months ago
    Collector specimens of millerite are full of personality, often fuzzy-looking rays or clusters of dark or brassy metallic fibers like this one from Halls Gap, Lincoln Co., Kentucky, USA. Millerite is nickel sulfide, and can be an important ore of nickel when found in high enough concentrations. Halls Gap is a well-known locality for millerites in quartz-lined geodes and pockets, but is reportedly closed or cleaned out these days. Erin Delventhal collection and photo. ICYMI: Each  #mineralmonday  we present a mineral species with some history and science, following along the order presented in Frederick Pough's definitive Field Guide to Rocks and Minerals; currently working through the sulfides!  #minerals   #crystals   #sulfides   #millerite   #science   #mineralcollecting   #geologyrocks 
  • by friendsofmineralogy 2 months ago
    Birefringence is defined as the optical property of a material having a refractive index that depends on the polarization and propagation direction of light. In plain terms, this means that a ray of light will be split by polarization into two paths. This often causes what is called "double refraction" when two images can be seen where once was one. This property can be useful in identifying minerals, because not all minerals are birefringent, and the different minerals have different refractive indices depending on their crystal structure. This piece of polished optical calcite shows a clear example of this property. Although "birefringence" is written three times on the paper underneath, the word shows six times through the crystal. As the crystal is rotated, the words also appear to rotate as the angle of polarization changes relative to the eye. Birefringence is a very useful property. You're most likely reading this text right now through the polarized light of a flat panel liquid crystal display. It is even used in medical diagnostics. For example, gout patients' painful joints are caused by accumulated crystals in their joint fluids. The birefringent properties of these crystals helps in diagnosis, because monosodicum urate crystals are negatively birefringent, calcium pyrophosphate crystals shows weak positive birefringence, and the colors of these crystals will change depending on the filters used.  #minerals   #crystals   #science   #birefringence   #calcite   #mineralcollecting   #geologyrocks 
  • by friendsofmineralogy 2 months ago
    Looking for a great introduction to studying mineralogy? One that we recommend is "Mineralogy for Amateurs" by John Sinkankas. Sinkankas covers subjects ranging from the history of mineralogy, an overview of atoms and how they arrange within (and thus affect) minerals, and classification schemes of minerals to crystallography and crystal growth, the physical and optical properties of minerals, formation and association of minerals, and identification procedures and tests. The latter portion of the book is a section of descriptive mineralogy, listing properties and information about a wide range of mineral species you might encounter. If all of that sounds like it might be too much and you're a little intimidated - it's okay! Sinkankas' writing style takes even the toughest concepts and explains them in a way that is approachable to everyone - this is the go-to starter guide for anyone looking to learn something more about the fascinating world of minerals. Pro tips: this same book was also published with a different cover simply as "Mineralogy." The social media team went to great lengths to compare our various different-looking copies to verify they contained the same material! Because it is long out of print, online sellers may charge quite a bit for any of these editions, however it can frequently be found for much more reasonable prices at neat old used bookstores and mineral shows, so keep an eye out! : Jessica Robertson  #minerals   #mineralogy   #books   #antiquebooks   #geologyrocks   #mineralcollecting