MUSCOVITE

HISTORY, NAME, LOCALITIES: Muscovite has been known since antiquity when it was called “white mica” and used in powdered form to whiten paints.  In 1850, it was assigned its name, which stems from the Russian principality of Muscovia (Moscow), where thin sheets called “isinglass” were used as a substitute for glass in windows and ovens.  Notable collecting localities are found in Namibia, Russia, Brazil, Pakistan, Malawi, Austria, Madagascar, and the United States (Maine, Vermont, South Dakota, Colorado, New Mexico, California, Virginia).

MINERALOGY, PROPERTIES, OCCURRENCE: Muscovite [basic potassium aluminum silicate, KAl₂ALSi₃O₁₀(OH)₂], pronounced MUSS-coh-vite, crystallizes in the monoclinic system as thin, tough, elastic, sheet-like crystals aligned parallel to its perfect, one directional cleavage.  Muscovite is a phyllosilicate mineral with a Mohs hardness of 2.0-2.5, vitreous-to-pearly luster, specific gravity of 2.7-3.0, and tendency to form aggregates of well-developed crystals called “mica books.”  Muscovite cleaves easily into thin, semi-transparent, silvery-white sheets.  As an abundant rock-forming mineral, muscovite is an essential component of many igneous, metamorphic, and sedimentary rocks and achieves its best crystal development in granite pegmatites.

METAPHYSICAL PROPERTIES; LORE, USES: Metaphysical practitioners believe that muscovite aids problem solving, stimulates quickwittedness, and alleviates anger, stress, and self-doubt.  Because of its low coefficients of friction and thermal expansion, inertness, and excellent heat- and electrical-insulating properties, muscovite has many uses in industry and is mined extensively.

COLLECTING INFORMATION: Muscovite is collected for its unusual crystal forms, usually as composite specimens in association with such pegmatite minerals as beryl, quartz, and microcline.

FLUORITE

HISTORY, NAME, LOCALITIES: Fluorite was used as a metallurgical flux as early as 500 B.C.  Its name stems from the Latin fluere, meaning “to flow,” alluding to its ability to reduce the melting temperature of metals in smelting processes.  Notable sources are China, Russia, England, Mexico, Canada, Peru, and the United States (Kentucky, Illinois, Colorado, Oklahoma).

MINERALOGY, PROPERTIES, OCCURRENCE: Fluorite [calcium fluoride, CaF₂], pronounced FLOR-ite, crystallizes in the cubic system as well-formed, often-twinned cubes and less often as octahedrons; it also occurs in massive, granular, and botryoidal forms.  It has a Mohs hardness of 4.0, perfect cleavage in four directions to form octahedrons, a specific gravity of 3.0-3.2, and is transparent to translucent.  Pure fluorite is colorless or white, but impurities impart a wide range of pastel colors, notably purples and greens.  Fluorite occurs in several mineralogical environments, including epithermal veins, hydrothermal replacement deposits, carbonatites, granite pegmatites, and contact metamorphic rocks

METAPHYSICAL PROPERTIES, LORE, USES: Medieval physicians prescribed powdered fluorite to treat kidney disease and arthritic pain.  Modern metaphysical practitioners use fluorite to calm the spirit and mind to prepare for meditation, increase objectivity and concentration, and clarify the decision-making process.  Fluorite is mined extensively as the primary source of fluorine and also serves as a metallurgical flux.  Massive fluorite is carved into decorative objects.

COLLECTORS’ INFORMATION: Fluorite is widely collected for its perfect cubic-crystal development, large crystal size, wide range of colors, and interesting and attractive mineralogical associations in composite specimens.