Malachite: Malachite is a bright green, basic copper carbonate. It appears as fibrous, radiating aggregates with silky to dull luster, and its crystals are adamantine. Acicular crystals are common. It commonly occurs as a green film on other copper minerals and as botryoidal or reniform masses with concretionary, banded structure and emerald green color. The color of the glassy, lustrous crystals is dark (read full)

Pearl: Pearl is one of four main ornamental materials that are classified as "organic" gems, the other three being coral, ivory, and amber. About 92 percent of pearl is calcium carbonate, in the form of aragonite crystals, held together by an organic substance (concholin), which is identical to the horny outer layer of oyster shells, plus a small quantity of water. Mother-of-pearl has a simila (read full)

Calcite: Of all minerals, calcite is by far the richest in forms. It appears as rhombohedral, scalenohedral, or prismatic crystals, often intergrown or twinned. It occurs in masses, colorless or in white, pink, green, or yellow, and often visibly thermoluminescent (emits light when heated). Like quartz, calcite often has twinned structure caused by temperature and stress changes. It is semi-hard, wit (read full)

Cerussite: Cerussite is a colorless carbonate of the aragonite mineralogical classification. It appears as colorless or white crystals with grayish tints, elongated and generally twinned to form a reticulated network with 60-degree angles, as stubby, tabular crystals in star- or heart-shaped twins. It can also be grey, greenish, or blue as a result of inclusions, such as lead, or copper. Impure cerussite is (read full)

Onyx: Onyx is a translucent to semitransparent variety of Agate, which in turn is a variety of Chalcedony or cryptocrystalline quartz that is porous and consists of straight or parallel banded agate of alternating shades of milky white and black, gray and black, black and red, white and red, white and brown. The term onyx has been erroneously applied as a suffix to Brazilian onyx, Mexican onyx, Orient (read full)

Rhodochrosite: Rhodocrosite is a manganese carbonate, a mineral of the calcite series with a hexagonal crystal system. It is isomorphous with calcite and siderite. It occurs as semitransparent, rhombohedral crystals with poor luster, frequently saddle-shaped, growing into druses, or as concretionary masses, sometimes with irregular, contorted veining. It has low hardness and perfect rhombohedral cleavage. Norm (read full)

Coral: Corals are the supporting framework of small polyps. Each coral polyp, a tiny marine animal that lives in enormous colonies, extracts calcium carbonate from the sea and exudes it through their bases to build a protective home around and above itself. Each generation of polyps dies in its protective home and each succeeding generation builds on top of its predecessor. They precipitate calcareous m (read full)

Aragonite: Aragonite is made from calcium carbonate and found near sedimentary rocks. Colors include clear (when free from impurities), yellow, blue, and even pink. Aragonite can be found in Turkey, France, United States,the bahamas and many other places around the world. Aragonite sand isn't necessarily mined but rather gathered from locations in and around reef systems. This sand is then stored and pack (read full)

Danburite: Danburite is a silicate of clear, prismatic crystals, with wedge-shaped terminations. It is occasionally pale yellow, a variety of gemstone feldspars group that resembles topaz. It is very hard, heavy, and has a transparent to vitreous to greasy luster. It fuses easily into a colorless glass, coloring the flame green, has a luminescence that is sky blue to pale blue-green, and also shows red therm (read full)

Vesuvianite: Vesuvianite is a hydrous calcium magnesium aluminum silicate with a tetragonal crystal system. It is the preferred name used by mineralogists for all transparent varieties of Idocrase, the name used by gemmologists. It is a gem mineral that appears in diverse colors, and thus is prized by collectors. A compact green variety of vesuvianite that looks like jade is known as californite. A greenish-b (read full)

Smithsonite: Smithsonite is a mineral in the group of Nitrates, Carbonates, Borates, with a hexagonal crystal system. It appears uncommonly in rhombohedral or scalenohedral crystals. But most of the time it appears with curved faces, like a thick creamy aqua-green mixture poured on rock and left to aggregate in clusters shaped like bunches of grapes, rounded, kidney-like, or to form like elegant icicles, and (read full)

Taaffeite: Taaffeite is a very rare beryllium magnesium aluminum mineral. No other mineral has both beryllium and magnesium in its composition. It is one of the few gems to be discovered as a faceted stone instead of a rough, as most gemstones are. Rarely cut as a gem, taaffeite looks like a mauve-colored spinel, and its absorption spectrum is similar to it. But gemologists know they've found taaffeite when (read full)

Ivory: Ivory is an organic gem material, largely obtained from the tusks of African and Indian (Asiatic) elephants, but also from the teeth and tusks of the hippopotamus, walrus, and other mammals. Like bones, it consists mainly of calcium phosphate in the form of oxyapatite and a small quantity of calcium carbonate, bound together by large amounts of the proteinaceous organic substance dentine, to form (read full)

Shell: Shell is the hard, protective, outer layer covering of certain creatures found in saltwater or freshwater, such as mollusks, snails, and turtles. This layer consists of calcium-carbonate and chitin, secreted by the soft tissue mantle of most mollusks. The inner surface of the shell is made from smooth nacre which covers the mantle.
Shell is used as inexpensive material for various purposes (read full)

Sodalite: Sodalite is a sodium aluminum silicate chloride in the Sodalite group with an isometric crystal system. Its royal blue forms are the best known. As a mineral, it is a principal component of lapis lazuli. It appears very rare as dodecahedrons, crystals with 12 faces, but usually it shows as compact masses, bright blue, white or gray with green tints. It is unsaturated and rarely appears with inclu (read full)

Zoisite: Zoisite is a hydrous calcium aluminum silicate in the Epidote group, with an orthorhombic crystal system, three crystal axes at right angles to each other, all of varying lengths. It appears in elongated, prismatic crystals, with fine parallel lines on the prism faces and usually poorly terminated. It also appears frequently in formless grains, poorly-defined crystals, rodlike aggregates and gran (read full)