HISTORY, NAME, LOCALITIES: Although known since antiquity, calcite’s many confusing crystal habits precluded recognition as a species until 1845. Its name stems from the Greek chalx, meaning “lime.” Calcite is found worldwide; notable collecting localities are in England, Iceland, Germany, India, and the United States (Tennessee, Missouri, Michigan, New Jersey).
MINERALOGY, PROPERTIES, OCCURRENCE: Calcite [calcium carbonate, CaCO3], pronounced CHAL-site, is the most abundant carbonate mineral. It crystallizes in the hexagonal system (trigonal subsystem); crystals are usually rhombohedral, scalenohedral, or prismatic with a unusually wide variety of habits. It has a Mohs hardness of 3.0, perfect cleavage in three directions to form rhombohedrons, vitreous-to-dull luster, and a specific gravity of 2.7-3.0. It is usually white or colorless, but impurities create a wide range of pale colors. Calcite develops in many mineralogical environments, including pegmatites, carbonatites, chemical and sedimentary rocks, metamorphic rocks, and hydrothermal veins.
METAPHYSICAL PROPERTIES, LORE, USES: According to metaphysical practitioners, calcite enhances learning abilities, reduces fear and stress, removes negative energies, and promotes creativity and imagination. Calcite is the primary mineral component of limestone, which is mined in huge quantities for use as dimensional stone, in cement, and as a metallurgical flux; and marble, which serves as a dimensional stone and sculpting medium. Banded, massive forms of calcite, known as “marble onyx,” are fashioned into ornamental objects.
COLLECTORS’ INFORMATION: Calcite specimens are widely sought by collectors for their remarkable variety of crystal habits and colors, unusual size, affordability, excellent crystal development, and, in composite specimens, interesting associations with many other minerals.
HISTORY, NAME, LOCALITIES: Colemanite, pronounced COLE-man-ite, was identified as a new mineral species in 1881 and named for William Tell Coleman, an American merchant and borax miner of the period. Colemanite is collected in Chile, Turkey, Argentina, and the United States (California, Nevada).
MINERALOGY, PROPERTIES, OCCURRENCE: Colemanite [hydrous calcium borate, Ca2B6O11·5H2O] crystallizes in the monoclinic system as short, prismatic or equant crystals, and in massive, compact, drusy, and incrusting forms. It is usually colorless or white, but may exhibit pale shades of brown and yellow. Colemanite has a Mohs hardness of 4.5, a vitreous-to-dull luster, perfect cleavage in one direction, an uneven fracture, and a specific gravity of 2.4. Colemanite occurrences are restricted to evaporite-type, chemical-sedimentary rocks; it forms from the repetitive evaporation of aqueous solutions of mixed borates in closed, saline lakes.
METAPHYSICAL PROPERTIES, LORE, USES: Because of its softness and solubility in water, colemanite has no use in jewelry. It is occasionally faceted into collectors’ gems. Colemanite is one of the four major borate ores that are mined extensively in California for use in detergents, disinfectants, soaps, paints, medicinal compounds, and coated papers. For metaphysical purposes, colemanite is believed to aid relaxation and help those who use their energies in an overly focused manner to assess situations from a broader perspective.
COLLECTORS’ INFORMATION: Well-developed, sharply pointed colemanite crystals with complex face arrangements make attractive mineral specimens for display purposes.