Most are opaque with distinct colors and characteristically colored streaks.
This class of minerals includes the majority of ore minerals - those with economic value.
Bornite - isometric, usually massive form. Metallic luster which tarnishes purple and blue - which gives rise to the nicknames "purple" and "peacock ore". Color is usually diagnostic. An ore of copper, occurs in many places worldwide, especially South America in Chile, Peru, and Bolivia.
Galena - Isometric; Diagnostic features are: Cleavage, high specific gravity, luster, color, hardness, and streak. The most important lead ore, is/was found extensively in the Mo./Ks./Ok area called the Tri-State region, and many other areas - Mexico, Australia, Russia, Canada.
Sphalerite - Isometric, often as cleavable masses, crystal structure is analogous to diamond. Luster resinous; Streak yellow/brown; Color varies slightly from brown to black (blackjack) with increasing iron; Red (ruby zinc) when it contains little iron. Found in geodes in Lawrence county. The most important ore of zinc, found in US, Canada, Mexico, and Russia.
Chalcopyrite - Tetragonal; Copper pyrite, is softer than pyrite; is soluble in nitric acid, with separation of sulfur. Streak greenish black. The most commonly occurring ore of copper and one of its most important sources. Found in US, Mexico, Chile.
Pyrite - "fools gold" - Commonly cubic crystals, with striations on crystal faces. Brittle, harder than other yellow metallic minerals, greenish black streak. Easily altered to oxides of iron (limonite). Found widespread, has no economic value - but can indicate other ore deposits, esp. chalcopyrite.
One or more metals combined with oxygen.
Magnetite - Important iron ore - Diagnostic is color, hardness, streak, and attraction to a magnet. When naturally magnetic it is called lodestone. Sweden, Russia (Ural Mts)
Hematite - Derived from a Greek word meaning blood. Important iron ore - Diagnostic is streak (Reddish - brown, like dried blood) and density. US, Canada, Brazil.
- Abrasive and gemstone; Diagnostic is hardness and crystal form - hexagonal.
Red = ruby, Blue = sapphire.
US, Canada, Brazil, India
Limonite - low grade iron ore; common; found in Lawrence Co.; diagnostic is color, hardness, streak. Formed through decomposition of other minerals as well as other processes.
Bauxite - not a true mineral, but is a mixture. Pisolitic structure and density is diagnostic. Aluminum ore. France, Jamaica, Indonesia, Russia.
- From the Greek work meaning salt. Found as cubic crystals and massive
forms. Taste is unique. Common mineral, use is for food, but also in the
chemical industry (chlorine). US, Canada, China, Russia.
Salt domes. Salt glaciers in Iran.
- From latin "fleure" meaning "to flow" since it melts more easily than
other minerals with which it was often confused.
Used as a flux; not as important now; limestone is used. Small amounts are used for lenses in optics.
- One of the most common and widespread minerals, usually in crystals but
also in fine and coarse grained masses. Manufacture of cements and lime
for mortar; ornamental stone carvings. It is usually white or colorless,
but can be nearly any color.
Rhombohedral cleavage, hardness, strong effervescence.
- Crystals are sharp rhombohedrons, and form saddle-shaped clusters. Pearly
luster (if unweathered) and slight effervescence. Will show effervescence
in cold HCl better if powdered on a streak plate first. Massive rock
(dolostone) is distinguished from limestone by weaker effervescence.
Used as a building stone and as an ornamental stone and in certain cements.
Found in many areas of the world.
Malachite and Azurite - The only green (malachite) or blue (azurite) opaque minerals that effervesce. Copper ores, also used as jewelry if found with dark color. Streak to match their color. Widely distributed with copper ores.
Barite - From the Greek word meaning "heavy". Ore of barium, used in drilling industry, paint, and medicine. Distinguishing characteristics are a high specific gravity and good cleavage. Color is usually white to yellow, but can be light shades of blue, yellow, or even red.
- Several varieties of this exist, and occur as massive mineral and also
as crystals. Fibrous crystals in veins are called Satin Spar; crystals
are Selenite; massive is called rock gypsum. Alabaster is the fine grained
massive form. Usually colorless or white, but can be other colors from
impurities. Diagnostic characteristic is hardness and cleavages (when large
enough to see it).
Use is in wallboard and in molds and casts; also in soil conditioners.
One or more metals combined with (PO4).
- From the Greek word which means "to deceive", characteristic of its being
mistaken for other minerals.
Hexagonal crystal shape, hardness, and color (green to brown, blue is possible), poor cleavage. Widely found as an accessory mineral in all classes of rocks. Norway, Sweden, Canada, Russia.
The most important group of minerals; comprise over 25% of all minerals in earth's crust and many rock-forming minerals.
- The 2nd most common mineral in the earth's crust; Importance is as a
rock forming mineral, in jewelry, Mortar (sand), building stones,
paving, optics, and electronics (think QUARTZ watch....).
Occurs in many forms - and all colors. Crystalline (hexagonal) is rock crystal quartz, pink =rose quartz, yellow = citrine, black = smoky quartz, purple = amethyst, white = milky, green = adventurine;Tiger eye is quartz replacement of another mineral. Chalcedony, flint, chert, jasper, agate, bloodstone, and onyx are all varieties of cryptocrystalline quartz.
(Grains large enough to be seen with a microscope are microcrystalline; grains too small to be seen with a microscope are cryptocrystalline.)
Quartz is VERY common, and has arguably the most commonly seen crystal form as a result.
Diagnostic features are crystal shape, hardness (much harder than calcite), glassy luster, conchoidal fracture (calcite has great rhombohedral cleavage), and is sometimes striated on crystal faces.
Olivine - Named due to olive-green color; is a common rock forming mineral; clear green is a gemstone called peridot. Diagnostic is glassy luster, conchoidal fracture, hardness, and granular nature.
Garnet group - Name is derived from latin granatus, meaning "like a grain". This group has many varieties, and can appear in nearly any color - but all are isometric in form, dodecahedrons. Distinguishing features - crystal shape and hardness. Use is as gemstone and also as an abrasive.
- Difficult to identify until you learn what it looks like; color varies,
commonly black or brown, but can be a gemstone as blue, pink, or green
if transparent. Long slender crystals typify the black variety called Schorl
tourmaline, which is the most common.
Used in pressure gauges due to it's piezoelectric properties, and also gemstones.
Diagnostic features: hardness, crystal form, and no cleavage (hornblende has very good cleavage).
Pyroxene group - Augite - Name - Augite means "luster" and Pyroxene means "stranger to fire" which is a misnomer because it was thought not to occur in igneous rocks. Uses are: Rock forming mineral and a gem. Distinguishing features: Imperfect cleavage at 930 and 870, color, luster and hardness.
Amphibole group - Hornblende - Widespread and important rock forming mineral; distinguished from Pryoxenes by the angle of cleavage - 560 and 1240 respectively, dark color, luster, and 6 sided cross-sections of crystals. More common in plutonic rocks than volcanic rocks.
Kaolinite - named after Chinese hill where it's found. Clay mineral, very soft, rubs off easily, smells like soil or clay when breathed on. Used in fine china, pottery, and ceramics.
Talc - name origin in doubt - probably arabic "talk". Used in baby powder (talcum powder), cosmetics, and many others. Distinguished by hardness and feel.
- name - from Muscovy -glass, due to its use as a substitute glass in Old
Russia (Muscovy). Mica was from latin "micare" meaning "to shine". Distinguishing
features: Color, tenacity (flexible), hardness, cleavage.
Uses include insulation in electrical equipment and houses, wallpapers, lubricants, and old wood stoves as "isinglass". Is a rock forming mineral.
- The same general characteristics as muscovite, except black.
(Other varieties are lepidolite - lavender color, chlorite - green color, and others)
Microcline feldspar - Name - from 2 Greek words meaning "Little inclined" referring to the slight variation from 900 of the cleavage angle. (K-spar) Forms probably the largest known crystals - 2000+ tons for a single crystal in the Ural Mountains in Russia. Colorless, white, flesh, green (amazonite). Used in porcelain, and is a rock forming mineral.
Albite - Anorthite - Plagioclase feldspars (Na - Ca spars) Have striations that microcline does NOT have along cleavage surfaces.
This may be the end - If I missed any, let me know and I'll give extra credit.