CALCITE PROPERTIES: Calcite is often the primary constituent of the shells of marine organisms, e. Plankton (such as coccoliths and planktic foraminifera), the hard parts of red algae, some sponges, brachiopods, echinoderms, some serpulids, most bryozoa, and parts of the shells of some bivalves (such as oysters and rudists). Calcite is a common constituent of sedimentary rocks, limestone in particular, much of which is formed from the shells of dead marine organisms.
Approximately 10% of sedimentary rock is limestone. Calcite is also the primary mineral in metamorphic marble. It also occurs as a vein mineral in deposits from hot springs, and it occurs in caverns as stalactites and stalagmites.
Calcite may also be found in volcanic or mantle-derived rocks such as carbonatites, kimberlites, or rarely in peridotites. High-grade optical calcite was used in World War II for gun sights, specifically in bomb sights and anti-aircraft weaponry. Also, experiments have been conducted to use calcite for a cloak of invisibility. Microbiologically precipitated calcite has a wide range of applications, such as soil remediation, soil stabilization and concrete repair. Color - Colorless or white, also gray, yellow, green, Crystal habit - Crystalline, granular, stalactitic, concretionary, massive, rhombohedral.
Crystal system - Trigonal hexagonal scalenohedral. Twinning - Common by four twin laws. Cleavage - Perfect on three directions.Hardness - 3 (defining mineral). Luster - Vitreous to pearly on cleavage surfaces. Specific gravity - 2.71. Other characteristics - May fluoresce red, blue, yellow, and other colors under either SW and LW UV; phosphorescent. This item is in the category "Collectibles\Rocks, Fossils & Minerals\Crystals & Mineral Specimens\Crystals".
The seller is "rocksology" and is located in this country: US. This item can be shipped to United States.