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 1 day ago
    Chalcopyrite (copper iron sulfide) is the most common copper ore mineral. It is often confused with gold and pyrite, since all three are metallic and yellowish or brassy. But they are easily distinguished with a closer look-- pyrite usually crystallizes in cubes or octahedrons while chalcopyrite forms in the tetragonal system. They are all different hardnesses, too. While pyrite can't be scratched with a knife, chalcopyrite can, and gold is the softest of all and can be scrated with copper. This specimen is from Alice Mine, Clear Creek County, Colorado, USA, one of the classic Colorado localities for Chalcopyrite, often producing brilliantly metallic twinned specimens like this one. Photo credit: 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!
  • by friendsofmineralogy 5 days ago
    Geology of a...Pumpkin? Yes, of course pumpkins on their own are biological, not geological. However, a lot of earth science goes into the pumpkin you pick out of a seasonal supermarket display or those at a very instagrammable commercial pumpkin patch. Pumpkins are frequently grown in abundant sun and water on the rich soil of farmland along river floodplains, but because a whole lot of nice plump gourds need a lot of additional nutrients, supplemental fertilization is usually needed. Different types of fertilizers are used, including nitrogen fertilizers, which help to produce healthy vines and leaves in the early growing season, and phosphate fertilizers, which help produce lots of pumpkin blossoms. Potassium rich fertilizers may also be used to help make heavy fruit. Nitrogen fertilizers are often made from manure, fish wastes, and other nitrogen rich material. Phosphate fertilizers are derived from phosphate rock that contains apatite group phosphate minerals. "Time-release" fertilizers can be a sort of technological combination of the two, in which nanoparticles of hydroxyapatite are coated with urea. This combination can target the delivery of both nutrients to the soil when they are needed in the growing cycle. Most of the world’s current production of phosphate rock is mined from sedimentary deposits formed by deposition of phosphate-rich materials in marine environments--deposits in Florida currently supply up to about 25 percent of total world phosphate rock production. And of course, petroleum is also needed for the fuels that take supplies and workers to the fields and that bring pumpkin crop to market. That's a topic for another day, but a note: more than a billion pounds of pumpkin get tossed into U.S. landfills every year. Pumpkins thrown into landfill or allowed to rot outside contribute to greenhouse gases like other rotting food waste. So please consider donating your used pumpkins to community pumpkin collection programs that will turn them into compost, reuse them as animal feed, or even turn them into biogas that can be used to generate electricity.  #science   #pumpkins   #minerals   #geologyrocks   #resources  FM graphic: Erin Delventhal
  • by friendsofmineralogy 1 week ago
    Sphalerite is zinc iron sulfide and an ore of zinc. It can vary in appearance, and was named from Greek word sphaleros, meaning "deceiving", due to the difficulty of identification. When the iron content is high, sphalerite is an opaque black variety called marmatite. It is also sometimes called ruby blende, zinc blende, or black-jack depending on color and appearance. Cleiophane is a gemmy, yellow to green variety. Zinc is one of those terribly useful metals, used in batteries, galvanization, nutrient supplements, zinc oxide sunscreens, and much more. Around 95% of all primary zinc is extracted from sphalerite ore, but because sphalerite can also include variable trace elements, it is also a source of other metals like gallium, indium, and germanium. Sphalerite is one of the most common sulfide minerals, and it is found worldwide and in a variety of deposit types. Each of the specimens in our image includes sphalerite, and together represent four continents. Backlighting of translucent specimens can reveal red, orange, green, and yellow colors-- sometimes multiple colors in the same crystal! Photo credit: 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!
  • by friendsofmineralogy 2 weeks ago
    National  #Fossil  Day! Why do fossils exist? Because they are the remains of former living creatures, turned to stone. What is stone made of? Minerals! So, Friends of Mineralogy wishes you a happy National Fossil Day. The million dollar question is this: can fossils be considered pseudomorphs? Though this might come as a shock in context of the typical modern concept of a “pseudomorph,” (a “false form” resulting strictly from one mineral replacing another mineral) the first usage of the word is found in René Just Haüy’s Traité de Mineralogie (1801). Haüy describes mineral bodies that owe their outward appearance to circumstances beyond their own crystallization or formation (“pseudo” = false, “morph” = form). The text goes into great length about fossils (in particular fossil shells and petrified wood), with only a brief mention at the end of minerals replacing other minerals. Thus, historically, it could be argued that the term  #pseudomorph  originated to describe fossils with mineral replacements as simply an afterthought. Photo: Calcite ps. Snail • Atienza, Guadalajara, Castile-La Mancha, Spain • 5.1cm • Erin Delventhal collection and photo
  • by friendsofmineralogy 2 weeks ago
    Galena (lead sulfide) is the main ore of lead. It's been used since antiquity (as far back as 9,000 years ago) since lead can be smelted from galena in an everyday wood fire. Galena also can contain impurities of silver-- if heating is prolonged and the smelted lead is oxidized into powdery ash, a small drop of pure silver may remain. In this way, ancient lead mines were also silver mines. Galena is one of the most abundant sulfide minerals, found worldwide--the specimens in our image represent four continents. Galena crystallizes in the cubic system and often is found in massive deposits, or crystals in cubes or octahedrons. The galena crystals in the center specimen shown here (from Dal'negorsk, Primorskiy Kray, Russia), are twinned into sharp triangular or hexagonal crystals that are almost as shiny as mirrors. Photo credit: 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!
  • by friendsofmineralogy 3 weeks ago
    Martine de Bertereau was the first recorded female mineralogist. With her husband Jean de Chastelet, she traveled extensively through Europe studying mines and mineral deposits. In 1626, at the request of King Henry IV, the Bertereaus established a base in Brittany to survey France for new mines to revive the French mining industry. At that time, the sciences of mineralogy and chemistry were still intertwined with alchemy, and mining prospectors sometimes included astrology-based techniques and dowsing. While in Brittany, provincial clergymen suspected them of sorcery and they searched their châteaux looking for incriminating material. Although nothing was found they were temporarily forced to leave France. Martine wrote two pamplets on her practice and theory of mining. The second, Restitution de Pluton, is an appeal to Cardinal Richelieu to be paid for their completed work, and also details some of her mine prospecting practices, like observing the local vegetation and water, watching for rising vapors, and dowsing and divining instruments. It is possible that de Bertereau wanted to keep her real prospecting techniques secret by confusing the reader with inclusion of divining and astrology, or used these techniques as a sort of theatrical proof of her skill. It is thought that the demand for money did not please the King. Charges of witchcraft were moved against them, and Martine and her family were imprisoned. While in prison Martine did not give up her passion. At one point, Martine scared a visitor with a 'magical' transformation, which she explained was a demonstration of the ‘végétal’ of silver and mercury, which grew and regenerated in a flask. This demonstration was probably a "Diana's Tree" precipitation of metallic silver from a solution of silver nitrate with mercury, like the one shown in the background of our image. The couple died in prison around 1642. France's mining industry was again in disarray. Other mining experts fled to other areas of Europe, and in 1667, it was remarked that there was nowhere in France a skilled mining expert to be found, only pretenders.  #history   #alchemy   #mining   #minerals   #silver   #witchcraft   #science 
  • by friendsofmineralogy 3 weeks ago
    Bornite is a copper iron sulfide and an important copper ore. It's one of those minerals that usually forms as massive material and has been known by many names including "purple copper ore," "variegated copper ore," "buntkupfererz" and "phillipsite." In 1845 it was officially named "bornite" by Wilhelm Karl von Haidinger in honor of Ignaz von Born, an Austrian mineralogist. Tarnished bornite can have a purplish sort of iridescence, however, the strong bright blue and purple "peacock ore" labeled as bornite in some rock and gift shops is very often chalcopyrite treated with acid rather than bornite. Bornite as a mineral, and especially as crystals, is more unusual than chalcopyrite. This excellently crystallized "tree" of bornite is from Carn Brea Mine, Pool, Carn Brea, Cornwall, England, UK. Carn Brea Mine was one of many 19th century mines in Cornwall that helped supply the raw materials for the industrial revolution. In 1847 alone, Carn Brea produced 10,372 tons of copper. Over the following years, Carn Brea amalgamated with neighboring mines as production decreased. The Carn Brea section closed in 1913-14.  #bornite   #sulfides   #peacockore   #copper   #minerals   #geologyrocks   #mineralcollection   #rockcollection  Photo credit: 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!
  • by friendsofmineralogy 4 weeks ago
    Detail from an allegorical painting titled "Mineralogy," in which a goddess sits among a crowd of mythological figures, with babies or cherubs at her feet holding minerals and rock hammers. Coloured stipple engraving by J. Chapman for the Encyclopaedia Londinensis, 1817. Start 'em young!  #mineralogy   #crystals   #art   #history   #mineralcollecting 
  • by friendsofmineralogy 4 weeks ago
    Chalcocite: copper sulfide. Stunning, shining crystals of chalcocite like these from Mammoth Mine, Queensland, Australia are unusual for the species. Much more often, the mineral occurs as massive ore deposits. Chalcocite is an important copper ore known for centuries, and has a variety of historical names to match, including chalcosine, redruthite, vitreous copper and copper-glance. Photo credit: 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   #chalcocite   #copper   #geologyrocks   #minerals   #mineralcollecting   #crystals 
  • by friendsofmineralogy 1 month ago
    September's birthstone is sapphire! One of the most famous sapphires of all is the Star of India, a 563-carat star sapphire. Mined in Sri Lanka and now located at the American Museum of Natural History in New York City, the Star of India is a historic gem that is also a dazzling example of the phenomenon of 'asterism'. Sapphire is a variety of the mineral corundum (aluminium oxide, α-Al2O3). Corundum crystallizes in a hexagonal system, with elongated, six-sided crystals. Star sapphires are included with microscopic inclusions of rutile (titanium dioxide) that are arranged perpendicularly to the rays of six-fold symmetry. A polished cross-section of this crystal can therefore reflect a pattern of a six-sided star, which appears to move and shimmer with slight changes in the angle of reflected light. The Star of India was among several gems commissioned from mineralogist George Kunz by J.P. Morgan in the early years of the 1900s. Kunz wrote in 1913 that the Star of India "has a more or less indefinite historic record of some three centuries," however, details of this historic record are now unknown. The Star of India's fame was increased even higher when it was one of several noted gems stolen from the American Museum in October 1964. It was recovered in early 1965 and returned to the museum, where it remains on display today. Photo credit: Kelly Nash  #sapphire   #corundum   #gemstones   #crystals   #science   #asterism 
  • by friendsofmineralogy 1 month ago
    Acanthite! Ever wonder what the dark tarnish is on your silver jewelry? That tarnish is the result of the reaction of silver with sulfur-containing molecules in the air and is silver sulfide: chemically the same as acanthite, the stable form of silver sulfide below 177 °C. The "acanthite" name comes from the Greek word meaning "thorn", which is reminiscent of its crystal shape. The sulfides, which tend to crystallize with a metallic luster and to be more brittle than the native metals, are of great economic importance, because many metal ores are in this group. Some field guides lists argentite, not acanthite, as the primary silver sulfide. These names are sometimes used almost interchangeably, however, because argentite is the stable form of silver sulfide above 177 °C, the only stable form in normal air temperature is acanthite. So, if you see a speciment for sale as "argentite", know it is really an Acanthite pseudomorph after Argentite. Photo credit: 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   #argentite   #acanthite   #geologyrocks   #minerals   #mineralcollecting   #crystals 
  • by friendsofmineralogy 1 month ago
    We here at Friends of Mineralogy wish you a very happy National Collect Rocks Day! We don't need a special day to appreciate our earth's treasures, but we love an excuse to get out there and add to our collections. How will you be celebrating this fine holiday?  #minerals   #crystals   #geologyrocks   #mineralcollection   #rockcollection 
  • by friendsofmineralogy 1 month ago
    Pliny the Elder, naturalist and Roman military commander in the first century AD, left an incredible legacy in his Natural History, a 37-volume encyclopedia of the collected knowledge of natural history of the time, sourced from personal experience, his own prior works (most of which have been lost), and extracts from other works. Book XXXIII of the Natural History is all about metals and minerals. Pliny was the first to record the correct origin of several earth materials, including as amber as the fossilized tree resin, and made a very early venture into crystallography by describing the octahedral shape of diamond. He was also careful to caution readers about the "considerable difficulty in distinguishing genuine stones from false" and to be wary of fraud by unscrupulous folks who may dye crystal to imitate "smaragdus" (emerald) or other precious stones, or who make sardonyx (banded agate) by gluing together slices of other stones. It is sometimes mentioned that Pliny recommended amethyst as a treatment for drunkenness, but that's not quite right. After noting that this information is one of "the falsehoods of magicians," he states that these sorts of recommendations are "statements which, in my opinion, they cannot have committed to writing without a feeling of contempt and derision for the rest of mankind." You tell 'em, Pliny! Of course, he did not get everything correct to our modern eyes, and included a variety of "facts" that are very entertaining today, for example that all precious stones are "improved in brilliancy by being boiled in honey." It's pretty good reading for an ancient encyclopedia, highly recommended. Pliny died when ventured too close to the shores of Herculaneum out of a scientific interest in the eruption of Mount Vesuvius in 79 CE. What a classic.
  • by friendsofmineralogy 1 month ago
    Graphite wraps up our  #mineralmonday  trip through the native elements. Like diamond last week, graphite is pure carbon. The difference results from carbon crystallization at much lower pressures and makes diamond and graphite the two naturally occuring allotropes of carbon. Instead of crystallizing in the isometric system like diamond, graphite crystallizes into a honeycomb-like hexagonal sheets. Athough diamonds are of course much harder than graphite, the chemical bonds between carbon atoms in diamonds are actually weaker than those that bond graphite. In graphite, the carbon atoms are tightly bonded into sheets, but the sheets themselves are weakly bonded and can slide easily over each other -- not like the inflexible 3D lattice of a diamond. This makes graphite soft and slick and very useful. Graphite was widely used as a lubricant and coating in the 1500s. It was even key to the success of the English Navy during the reign of Elizabeth I. Fine graphite from Cumbria was used to line the molds for cannonballs, which made the cannonballs smoother so that they could fly farther and straighter. These days graphite is still an used as a lubricant in foundries and steelmaking and is an important component of break linings and batteries. Next week we start down the list of sulfides! Who is excited??? Photo credit: 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 native elements!  #diamond   #nativeelements   #minerals   #elements   #mineralcollecting   #crystals 
  • by friendsofmineralogy 2 months ago
    Listen up, kids. School is back in session! Today's lesson: The rocks that go into making the average no. 2 pencil. Yeah, you already know that pencil "lead" is actually graphite. But pencils never did contain lead. In the 1500s, most graphite came from Cumbria, England, in blocks that were cut to use as writing implements. Back in those early days of chemistry, graphite was thought to be a form of lead. The term had well stuck by the time it was sorted out. A pencil's ferrule (the metal bit that holds the eraser on) is usually aluminum. Although aluminum is the most common metallic element on earth, it's too reactive with other elements to occur by itself. Bauxite, a sedimentary rock with high concentration of aluminum oxides found in soils of the tropic and subtropic regions, is the primary source of all our aluminum. Bauxite is processed first into aluminum oxide and then into aluminum by electrolysis. Traditional 'pink pearl' type erasers are made of synthetic rubber, stabilized with sulfur, that have a fine pumice added as an abrasive. The pumice is the magic ingredient that makes them actually erase instead of just smudging marks around the paper. These erasers don't have to be pink. Back in 1916, the Eberhard Faber Pencil Co. sourced a particular Italian pinkish pumice that made their pinkish erasers much prettier than the other drab ones on the market. A tradition was born. Oh, also-- that pencil is yellow because Chinese emperors wore yellow and as of 1889, the best graphite was from China. When an enteprising pencil manufacturer wanted to market his pencils at the 1889 Paris Exhibition, yellow was his choice to help advertise the quality of his graphite and to capitalize on the association with royalty. It didn't hurt that the paint helped camouflage imperfections in the wood. The pencils were a hit and the other manufacturers followed suit once more. Historically, these yellow paints could have used pigments containing lead or chromium. But even though all pencils have nontoxic coatings these days, it's still best not to gnaw. You don't know where it's been. Hope you took notes! Yes, there will be a quiz.
  • by friendsofmineralogy 2 months ago
    Diamond: from the Greek word 'adamas', meaning invincible. Pure carbon in isometric crystals. Although known from antiquity, diamonds were only found in stream or riverbed deposits until the nineteenth century. Diamonds have been mined from these sorts of alluvial deposits in India for more than 3,000 years. Their origin was for a long time rather a mystery; Hindu folklore had it that diamonds were formed by lightning strikes. Following sparse deposits of diamonds up South African streams in the 1860s, more diamonds were found in "yellow earth" above hard diamond-bearing rock called "blue ground", later called kimberlite, after the mining town of Kimberley. The largest of these blue ground locations became the Kimberly Mine in 1871. The area quickly became the center of world diamond production, in only a few years yielding more diamonds than India had in over 2,000 years, although not without greed and obsession and exploitation and blood. This large crystal, approximately 1.5 cm on a size, is from the original Kimberley Mine, which closed in 1914. Kimberlites are an unusual type of volcanic rock that erupted from deep within the mantle and are most often found in the very old areas of continental crust. Not all kimberlite "pipes" have diamonds, either. Instead of the diamonds crystallizing within the formation as some other minerals do in their volcanic settings, diamonds are previously present within the mantle and are passengers on the kimberlite bus that brings them to the earth's surface. Many diamonds show signs of resorbtion that indicate they are partially dissolving during transit, so for something "invincible," it seems lots of them aren't arriving at the station. Still, it's ok, there's plenty. Diamonds are actually among the most common gems. Don't let the marketing fool you. Photo credit: 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 native elements!  #diamond   #nativeelements   #minerals   #elements   #mineralcollecting   #crystals 
  • by friendsofmineralogy 2 months ago
    Need some Sunday reading? New FM Bulletin! Lots of exciting new things are in the works. Link in bio to our website, find it under "Newsletters."
  • by friendsofmineralogy 2 months ago
    Mineral Identification 101: Part 3. Crystal Morphology (aka crystal shape or habit) Where hardness gave us clues, crystal shape can give us more certainty. Separate mineral species are defined by their chemical composition and their specific crystal structure. While we can't see the structure of the individual molecules, the structure of a mineral is expressed in the external shape of its crystals. So although our three mineral samples are all jumbles of clear crystals on matrix and therefore look superficially similar, close observation will give us the info we need. Last time we used hardness to differentiate the quartz from the calcite and fluorite. Quartz also almost always grows in six-sided prisms topped with a six-sided pyramid, confirming our suspicion from the hardness test. Fluorite and calcite, though-- how to tell apart, if hardness didn't help? A quick glance at a field guide tells us that fluorite has an isometric structure and usually crystallizes as cubes, and that calcite has a trigonal structure with over 800 different identified forms! That's intimidating, but a distraction to our current question, because the most common of those 800 forms are rhombohedrons and scalenohedrons-- definitely NOT cubic. So that's our answer here. The cubic crystals on the tan matrix are slightly modified at the corners but are classic fluorite cubes, and the more complicated shape crystals on the dark matrix are our calcite. WIN!  #mineralidentification   #crystals   #minerals   #science   #geologyrocks   #mineralcollecting   #mineralogy 
  • by friendsofmineralogy 2 months ago
    Crystals have habits? Mineral Identification 101 Part 3 coming tomorrow!  #minerals   #crystals   #mineralogy   #mineralidentification   #science   #sciencememes 
  • by friendsofmineralogy 2 months ago
    Sulfur. "There are few minerals with which it would be confused," according to Frederick Pough. It's true. In addition to the bright yellow color and several unique diagnostic properties, even well crystallized sulfur pieces like this Sicilian specimen often carry a little whiff of the distinctive rotten-egg odor of hydrogen sulfide, created in the reaction with humidity in the air. Although only a very small amount of hydrogen sulfide is created in this way, the odor is powerful and easily detected by our coarse human noses. Sulfur was called "brimstone" in antiquity, and lives on in that term in the Bible and the association with damnation and divine retribution. Sulfur is still mined in some parts of the world in volcanic areas that belch clouds of sulfurous gases that roar with a hiss, where it is easy to imagine devilish forces beneath, like in this photo of a traditional sulfur mine in Java. Sulfur mines in Sicily were the primary source of sulfur in ancient times. For millenia, conditions at the Sicilian mines were horrific, prompting Booker T. Washington to write in 1912 that "I am not prepared just now to say to what extent I believe in a physical hell in the next world, but a sulphur mine in Sicily is about the nearest thing to hell that I expect to see in this life." Fortunately, these mines closed after WWII and most commercial sulfur is now produced as a side product of other industrial processes. Sulfur crystals are fragile and are temperature sensitive as well as humidity sensitive. Cracks can be caused by temperature changes as simple as holding a cold specimen in a warm hand, so don't handle frequently. If you live in a humid environment, you should also consider keeping your sulfur crystals in enclosed containers with dessicant. Photo credit: Slide 1, Jessica Robertson; Slide 2, Lisa Cyr 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 native elements!  #sulfur   #minerals   #crystals   #nativeelements   #mineralcollecting   #geologyrocks   #mineralogy   #mineralspecimens