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)

Dolomite: Dolomite is similar to calcite and sits along side it in limestone. It usually occurs as a secondary mineral, formed by the reaction of magnesium-bearing fluids seeping through the limestone. It may be colorless, or white to cream and even yellow brown, sometimes pale pink. It has a vitreous luster and is translucent. The faces of dolomite crystals are often curved, sometimes so acutely that th (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)

Datolite: Datolite is a semi rare silicate mineral of the gadolinite group. It appears as surface-growing, short and stubby, prismatic, large crystals. Its crystal structure is monoclinic, as it has two axes of unequal length inclined to each other, with the third lateral axis at a right angle to the plane that contains the other two. Its aggregates are huge, granular, dense, fibrous, and has porcelaneou (read full)

Hessonite: Hessonite is the brown-orange variety of Grossular, a nesosilicate in the Garnet group, with an isometric crystal system. It appears with dodecahedral or trapezohedral crystals, cinnamon-brown to orange because of its iron content. Its color matches that of the oil of cinnamon. It also appears as golden-yellow, yellow-brown, or reddish-brown. It is very hard, heavy, fragile, has no cleavage. It (read full)

Lapis Lazuli: Lapis lazuli is composed of several minerals in small quantities - augite, calcite, diopside, mica, hauynite, hornblende, pyrite. Because of this some experts consider it a rock, more than a mineral. The main ingredient of Lapis lazuli is Lazurite. It has a uniform, massive, or sometimes granular appearance, with fairly distinct crystals. It is semi-opaque to opaque, with a surface that can take (read full)

Hambergite: Hambergite is a beryllium borate mineral in the classification of Nitrates, Carbonates, and Borates and is an extremely rare gemstone. It occurs as transparent colourless orthorhombic prismatic crystals which are usually well crystallized, sometimes twinned. Its colors range to white, white grayish, and yellowish white. Crystals are striated along the prisms. It is very hard and has one directi (read full)

Silver: Silver is a Native Element with an isometric system, a soft, white, precious metallic element of group 1 of the Periodic System with the symbol Ag. It appears as cubes, octahedrons, and dodecahedrons, and rarely as crystals. Native silver cubes are always small, usually displaying stepped faces, or in compact masses of twining branches, and wirelike forms of a silvery, gray-white color. Aggregate (read full)

Epidote: Epidote is widespread, forms a continuous series of minerals, ending with clinozoisite, which contains no iron. It occurs as crystals elongated and often striated parallel to length, and also as massive, fibrous, or granular habits. Epidote has a yellow-green color, ranges from yellowish-greenish to greenish-black. It has vitreous luster, and is transparent to nearly opaque. It has one perfe (read full)

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)

Emerald: Emerald is the most prized variety of the mineral Beryl. It sometimes fetches higher prices than diamond. It appears as pale green to bright green. Though it is the green variety of beryl, not all gem-quality green beryls are called emeralds; yellow-green stones are called "heliodors;"soft blue-green or even pale green specimens are called "aquamarines." The typical color of emerald is a bea (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)

Grossular Garnet: Grossular is a nesosilicate in the Garnet group, with an isometric crystal system. Together with uvarovite and andradite, the three are known as the "ugrandite garnets," an isomorphous series of calcium garnet minerals. It appears with dodecahedral or trapezohedral crystals of various colors; normally characterized by a green color, but also may be colorless, pale green or milky when pure, cinnam (read full)