HGMS Worldwide Minerals and Descriptions

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1 NAME ACTINOLITE ADAMITE on brown goethite, Mapimi, Durango, Mexico. ANHYDRITE APATITE - blue APATITE, hardness of 5 ARAGONITE - amber colored crystal ARAGONITE - twinned crystal from Clarendon, Texas. AZURITE, blue from Morenci copper mine in Arizona. The green is malachite. BARITE SAND ROSE or nodule, from Norman, Oklahoma. BERYL, small six-sided (hexagonal) crystals from New Hampshire. BIOTITE MICA CALCITE cut pieces of calcite onyx, Mexico. CALCITE crystals on matrix CALCITE, colored HGMS Worldwide Minerals and Descriptions DESCRIPTION Calcium magnesium iron silicate: This metamorphic mineral starts out as an impure limestone or dolomite. When the crystals are extremely small, this mineral is called jade. Zinc arsenate: a secondary mineral formed by oxidizing zinc sulfides and other primary ore minerals. A minor ore of zinc. The yellow varieties are fluorescent and phosphorescent. (Wash your hands after handling this mineral, even though it is not very soluble in water.) Calcium sulfate: Gypsum will alter to anhydrite by loss of water when the the rock is squeezed and heated by burial to a depth of 1000s of feet. Calcium phosphate: This blue apatite is found in an unusual rock called carbonitite, an igneous body composed primarily of calcium carbonate. Calcium Phosphate with some fluorine: Apatite comes from both organic and inorganic sources. Many living creatures (like sharks and humans) make their skeletons and teeth out of hydrated calcium phosphate. Their accumulated remains are mined for fertilizer. Inorganic apatite is found in igneous rocks. Calcium carbonate: It is difficult to tell this mineral from calcite since they are both calcium carbonate and both fizz in 5% HCl. The distinguishing feature is that aragonite has poor cleavage compared to excellent cleavage for calcite. Calcium carbonate, like calcite, but orthorhombic instead of hexagonal. Unless you have crystals, it is almost impossible to tell calcite from aragonite. Some organisms, like oysters, make aragonite hard parts. Copper carbonate: Azurite and malachite are common copper minerals. A hardness test is difficult because the azurite is a fluffy mass of crystals, which crush when you try a hardness test. Both azurite and malachite are important copper ores. Barium sulfate: Barite is a white mineral. The red sandstone in which they are found colors these roses. A small amount of barium gets stuck to the clay minerals that make up a marine mud deposit. When diagenesis transforms that mud into shale, some of the barium is expelled into the ground water. That ground water will be forced through a permeable sandstone layer on its way to the ocean and the barium will encounter sulfate from seawater and be precipitated as barite. Try a heft test and note that barite (density of 4.3) has a much greater specific gravity than quartz (density of 2.9) or calcite. Beryllium aluminum silicate: Beryl is really hard (H=8), right up there with topaz. Transparent, colorful members of the beryl family (green emerald, blue aquamarine, pink morganite) are prized as gemstones. Beryl is the only important source of the element beryllium. Potassium magnesium iron aluminum silicate: A common mineral in igneous and metamorphic rocks. The dark color comes from iron (muscovite mica is clear and does not contain iron). Calcium carbonate: This is another form of calcite that is deposited by dripping water in a cave. Calcium carbonate: Look at your specimen for broken tips on the ends of the crystals. You will see 3 directions of cleavage. Test the hardness to see that this mineral is harder than gypsum and softer than fluorite. Calcium carbonate: Small amounts of metals or minerals can color the normally clear calcite.

2 CALCITE, hardness of 3 Calcium Carbonate: A very common mineral that typically is precipitated by organisms like clams, which use it to make their skeletons. When large amounts of these biological products accumulate and get cemented together, the rock is called limestone. Calcite may be dissolved and re-precipitated by hot ground water as large and beautiful crystals. CELESTINE from Lampasas County, Texas. Strontium sulfate: The red color in fireworks is from strontium. A distinguishing It occurs in cavities in characteristic for this mineral is that it is heavy. You can do a specific gravity test to limestone. find that this mineral is 4 times the density of water, but first just try a heft test. Take a piece of celestine in one hand and a similar sized piece of calcite or quartz (density of 2.9) in the other and jiggle them. Compare it with siderite. CERRUSITE Lead carbonate: A secondary mineral from weathering of lead ore veins. Do not handle this mineral. CHALCOCITE Copper sulfide: A secondary mineral found in the upper parts of weathered copper ore veins. This mineral is easily reduced to copper metal and was probably important to early man. CHALCOPYRITE Copper iron sulfide: Commonly found in very large but low grade igneous ore bodies where it is concentrated by the "flotation process". The whole rock is ground to dust and then frothed up in a solution of pine oil. The sulfides stick to the froth CHRYSOCOLLA CHRYSOCOLLA, after azurite COPPER which is collected. Hydrous copper silicate: The blue-green color and the botryoidal growth (lots of tiny, radiating crystals that make a bubbly-looking mass) are typical. Chrysocolla s nice color and luster make it a semi-precious gemstone. Hydrous copper silicate: Silica rich solutions apparently altered the azurite (copper carbonate) crystal to copper silicate without changing the crystal shape. Native Copper: The weather of copper ore veins concentrates the copper in malachite, azurite, bornite and native copper. These ores were very important for early man to smelt for copper. CORUNDUM, hardness 9 Aluminum oxide: Corundum is found in silica-deficient, high temperature metamorphic rocks or in aluminum-rich igneous rocks. If silica is present, corundum will not form because aluminum silicates are much more stable. The diagnostic test for corundum is its hardness. You will find it harder than anything in this box, harder than any mineral but diamond. Minor impurities can color corundum red (ruby) or blue (sapphire). CROCOITE CUPRITE DOLOMITE EPIDOTE Lead chromate: This is a rare secondary mineral that is found where lead ores are found in veins in oceanic basalts (containing chrome minerals). Copper oxide: A rare secondary mineral from the upper part of ore veins. Calcium magnesium carbonate: The distinguishing characteristics for this mineral is that the crystals usually have a saddle shape and that the mineral will not fizz in 5% HCl solution. Calcium iron silicate: An extremely common mineral in igneous and metamorphic rocks. The color is so characteristic that sometimes it is called "pistacite" from the color of Pistachio nuts. FLUORITE, hardness of 4 Calcium Fluoride: Typically found in beautiful crystals in hydrothermal deposits (200 degrees C and 5000 PSI) along with metallic ore minerals. Ancient peoples discovered that fluorite ( flowing stone ) would make many ore minerals melt more easily. This mineral shows 4 directions of cleavage. FLUORITE, hardness of 4 Hydrous sodium calcium borate: This mineral is found in desert dry lake beds along with borax.

3 GARNET crystal from Malawi in Africa GOETHITE GYPSUM, roses from the Chihuahuan desert of northern Mexico. GYPSUM, hardness of 2 GYPSUM, sand crystals GYPSUM, satin spar HEMATITE HEMIMORPHITE, white to gray crystals in brown to black goethite, Mexico KYANITE in QUARTZ from Brazil Blue blades in a milky quartz matrix. LEPIDOLITE mica from Maine MALACHITE MICROCLINE, hardness of 6 MICROCLINE, hardness of 6 (var amazonite) MOLYBDENITE from Arizona MUSCOVITE Mica Aluminosilicate group with extremely variable cation substitution: Garnets occur in many rock types. Though only slightly harder than quartz, garnets are pretty tough. Because they break with a conchoidal fracture (like glass), making lots of little sharp pieces, crushed garnets are used to make sandpaper. When clear and a pretty color (red, orange, green) garnet is faceted as a gemstone. Hydrate iron oxide: When iron pyrite weathers, the iron sulfide is chemically converted to hydrated iron oxide but the external form stays that of pyrite. This form is called a pseudomorph or "false form" because the crystal looks like the former iron pyrite. Hydrated calcium sulfate: Gypsum grows in many crystal shapes. This kind grows in sand that is saturated with hard water and the calcium sulfate precipitates at the water evaporates. The white deposits on your showerhead are mostly gypsum. You will see that the hardness is the same no matter what shape the crystals are in. Hydrated Calcium Sulfate: A very common mineral that precipitates as seawater evaporates. The most common use is for making sheet rock wallboard. Hydrated calcium sulfate: This form of gypsum grows in sand where evaporation concentrates this barely soluble mineral and you can see amber sand inside. Hydrated calcium sulfate: This form of gypsum fills veins in rock and the crystals are always perpendicular to the sides of the vein. Iron oxide: Scratch this on an unglazed tile plate and you will see that finely divided hematite is red. It just looks black in crystallized form. Hydrous zinc silicate: Naturally colorless, hemimorphite is often colored by minor impurities. Even though it is a silicate, it is pretty soft, H=4.5 to 5. Aluminum silicate: formed from clay that is metamorphosed at high temperatures and pressures. Besides its blue color, the most diagnostic feature is that it is harder when scratched across to the crystals than parallel to them. A knife will make a scratch along the crystals but not across them. Lithium potassium aluminum fluosilicate: This mica is only found in pegmatites Copper carbonate: Azurite and malachite are common copper minerals. A hardness test is difficult because the azurite is a fluffy mass of crystals, which crush when you try a hardness test. Both azurite and malachite are important copper ores. Potassium Aluminum Silicate: Microcline is one of a family of minerals called feldspars. They are found in igneous rocks and weather to clay minerals. Note that there are two directions of cleavage at nearly right angles (micro-cline = little angle) to each other. Potassium Aluminum Silicate: Microcline is one of a family of minerals called feldspars. They are found in igneous rocks and weather to clay minerals. Note that there are two directions of cleavage at nearly right angles (micro-cline = little angle) to each other. The variety amazonite is green in color. Molybdenum sulfide: Found in igneous rocks and pegmatites. This mineral is very soft and is used as a high pressure lubricant. Potassium aluminum silicate: Muscovite is found in igneous and metamorphic rocks. The distinguishing characteristic of this mineral is thin, flexible sheets, which can be split off. It has a hardness of 2 to 2½.

4 OKENITE OLIVINE (peridote) tumble polished OPAL in volcanic rock Hydrous sodium calcium aluminum silicate: This mineral is in the zeolite family. It forms in basaltic rocks where water leaches out silica and deposits water rich minerals in cavities. This zeolite grows in a puff-ball shape. Magnesium iron silicate: This mineral is found in silica poor igneous rocks and makes up much of the minerals deep within the earth. Iron makes this mineral dark green. Hydrated silicon dioxide: Silica leaches out of the volcanic rock and fills the cavities. Sometimes the process is so regular that the opal spherules are deposited in a regular grid and this opal shows a beautiful play of colors. ORTHOCLASE (feldspar) Potassium aluminum silicate: Like microcline, this mineral has two directions of cleavage and nearly right angles. It is difficult to tell from microcline without a thin section. PHACOLITE (CHABAZITE) PYRITE, known as "fool's gold", from the silver mines of Peru. PYROLUSITE PYROMORPHITE QUARTZ, black QUARTZ, hardness 7 QUARTZ, jasper QUARTZ, rose QUARTZ, variety adventurine QUARTZ, variety amethyst - from Rio Grande do Sul, Brazil - from cavities in basalt. RAMSDELLITE RECTORITE RHODOCHROSITE Hydrous calcium sodium aluminum silicate: This mineral is in the zeolite family. It forms in basaltic rocks where water leaches out silica and deposits water rich minerals in cavities. Iron sulfide: diagnostic properties are its brassy gold color, its brittleness and, when present, its cubic crystals. Once a minor iron ore, most pyrite is mined today for its trace content of precious metals like gold and silver. Manganese oxide: This mineral leaves sooty black marks when you touch it. Lead chlorophosphate: A secondary mineral from weathering of lead ore veins. Silicon dioxide: Black quartz is clear quartz with black mineral inclusions. Silicon dioxide: Quartz is the most common mineral on the continents of the earth. Sand is primarily quartz that has eroded from somewhere else, like granites, and has been concentrated by rivers. When minerals cement the sand together, the rock is called sandstone. Quartz can be recognized by its hardness (it will scratch glass) and its lack of cleavage. Broken quartz looks just like broken glass, and is just as sharp. It grows in hexagonal crystals with striations on the sides. Many common forms of quartz (agate, chalcedony, flint, chert, jasper) are made of tiny crystals, the result of rapid crystallization. Silicone dioxide: When quartz crystallizes rapidly it typically incorporates iron minerals which are red or yellow. This variety of quartz is not nearly as well organized as agate. Silicon dioxide: Rose quartz is exclusively found in pegmatites and almost never in crystals. It commonly contains enough rutile to show a star on a properly cut stone. Silicon dioxide: This granular form of quartz has green mica between the grains. Silicon dioxide: The purple color is from iron. If you were to wrap this crystal in 10 layers of aluminum foil and heat it for 2 hours at 400 degrees F, it would change color to yellow as the iron changes oxidation state. Manganese oxide: This mineral leaves sooty black marks when you touch it. Hydrous sodium calcium aluminium silicate: Touch it. It feels like leather. The mineral has the structure of a mica but is not rigid. It is more like a clay mineral, but with more structure. Manganese carbonate: Occasionally this ore mineral is concentrated enough to form lovely pink masses which can be cut as a semi-precious stone.

5 RHODONITE ROSASITE RUTILE SCHEELITE SIDERITE SILVER SMITHSONITE, pinkish bubbly crusts, Mexico. SPHALERITE, dark brown to black, bright cleavage and dull crystal faces, with yellow chalcopyrite. STAUROLITE STIBNITE Manganese silicate: Rhodonite (hardness 5 ½ to 6) is usually found in metamorphic rocks where the heat and pressure create an environment in which the manganese dissolves out of low concentration sources like shale. It can form large masses of beautiful pink stone. You might mistake this mineral for the other common pink mineral, rhodochrosite (hardness 3 ½ to 4), except that rhodonite is much harder. Try a hardness test and see. Rhodonite is a manganese ore and is cut as a semiprecious gemstone. Copper zinc carbonate hydroxide: A secondary mineral from weathering of ore veins. Titanium dioxide: A high temperature mineral found in igneous and metamorphic rocks. The luster of this mineral is called adamantine (or diamond like). Calcium tungstate: This mineral forms at the boundary between an igneous body and the surrounding rock. It fluoresces brilliantly. Iron carbonate: Siderite can be found in sedimentary rocks where it precipitates from seawater as a cement. It also is found in hydrothermal ore veins where it forms in masses with good cleavage like the sample you have. This mineral is harder than calcite (hardness 3) and softer than fluorite (hardness 4). Try it. Native silver: Weathering concentrates silver from lead minerals with a small percentage of silver. Zinc carbonate: Minor amounts of cobalt color this specimen pink. Zinc sulfide: Sphalerite is the primary ore of zinc. It has good cleavage and a substantial heft. Iron aluminum silicate: Notice that this specimen is a cluster of crystals called a penetration twin. A mineral in metamorphic rock that grow at high pressure. Antimony sulfide: The elongated crystals of this mineral can be bent a little because the crystal structure will slip along glide planes. STILBITE occurs in cavities in basalt - from Siberia, Russia, Nova Scotia, Canada and India. Hydrous sodium calcium aluminosilicate. These crystals grow rapidly. Artificial zeolites are used in ion-exchange applications, such as water purifiers. SULFUR TALC, hardness of 1 THOMPSONITE TOPAZ, hardness 8 - When nicely colored (blue, yellow, pink) and transparent, topaz is a gemstone. native Sulfur: Volcanic fumaroles frequently have a halo of sulfur crystals around them. In Texas, sulfur is found in salt domes as a end product of bacterial reduction of gypsum (calcium sulfate). Hydrated Magnesium Silicate. This mineral is usually found in metamorphosed oceanic crust. It is so soft that your fingernail will scratch it. Ground talc is often used as baby powder. Hydrous sodium calcium aluminum silicate: This mineral is in the zeolite family. It forms in basaltic rocks where water leaches out silica and deposits water rich minerals in cavities. Aluminum fluohydroxysilicate: Topaz is found in pegmatite veins associated with granites. A pegmatite is the last material to crystallize as a large igneous body cools. Pegmatites frequently contain rare and beautiful minerals like topaz. Our specimens are rounded, water-worn pebbles collected from a stream in Brazil, so they do not show crystal faces. Topaz has a single direction of weakness, called a cleavage plane, which shows up if a pebble is broken.

6 TOURMALINE VANADINITE, tiny orange to red crystals from Arizona. VARISCITE VESUVIANITE WAVELLITE, green sprays on gray Big Fork chert. From Arkansas. WOLLASTONITE WULFENITE ZOISITE, pink with epidote (green), quartz (white to gray), Baja California. a complex series of compounds containing Calcium sodium magnesium lithium aluminum boron silicate: The mineral can be any color but always has the form of elongated trigonal (3 sided) crystals. This mineral is found in high temperature and pressure pegmatites and igneous rocks. Lead chloro-vanadinate: a secondary mineral formed by oxidizing lead ores in deserts. (Wash your hands after handling this mineral, even though it is not very soluble in water.) Hydrous aluminum phosphate: Found in desert climates where the weathering of shales concentrates phosphates that were adsorbed on the clays. Calcium iron magnesium hydroxide silicate: This mineral may form where molten rock (igneous) comes in contact with impure limestone, like at Mt Vesuvius in Italy. Hydrated aluminum phosphate: a secondary mineral (formed by breaking down phosphates or Al-rich metamorphic rocks). Its bright green, lustrous, radiating, fibrous crystals make it a sought-after specimen but it has little economic importance. Calcium silicate: A mineral of strongly metamorphosed impure limestones. The crystals are always needle like. Lead molybdate: A secondary mineral in dry climates from weathering of lead veins. Hydrous calcium alumino-silicate: forms in pegmatites and metamorphic rocks that form when high Ca rocks are subjected to considerable pressure. Crystals radiate from central points, indicating rapid growth.