HISTORY, NAME, LOCALITIES: Brookite, pronounced BROOK-ite, was identified as a mineral in 1826 and named in honor of British crystallographer and mineralogist Henry James Brook. Notable collecting localities are in Pakistan, Russia, Austria, France, Germany, Italy, Switzerland, Brazil, South Africa, Australia, and the United States (Arkansas, New Jersey, New Hampshire, New York, and Oklahoma).
MINERALOGY, PROPERTIES, OCCURRENCE: Brookite, rutile, and anatase are the three polymorphs of titanium dioxide (TiO2). Brookite, which is uncommon, crystallizes in the orthorhombic system as then, tabular-to-platy, sometimes sheet-like crystals with pseudo-hexagonal cross sections and parallel striations, and less commonly as six-sided bipyramids. It has a Mohs hardness of 5.5-6.0, a sub-metallic luster, poor one-directional cleavage, and a specific gravity of 4.1. It is transparent to nearly opaque, with colors ranging from brownish-black and reddish-black to brown, yellow-brown, reddish-brown, and amber. Brookite occurs mainly in alpine-cleft-type deposits (mineralized fissures in igneous rock) in association with anatase, rutile, titanite, and quartz. Lesser amounts of brookite form by hydrothermal alteration.
METAPHYSICAL PROPERTIES, LORE, USES: Brookite has occasionally served as a minor ore of titanium, a metal used to produce rigid, lightweight, high-strength structural alloys with high melting points and exceptional corrosion resistance. Although brookite has no use in jewelry, transparent crystals are occasionally faceted into collectors’ gems. Modern metaphysical practitioners believe that brookite helps to dispel apathy and lethargy, and aids in dealing with difficult situations.
COLLECTORS’ INFORMATION: Brookite is collected for its rarity, unusual colors, and distinctive crystal forms, and is most popular as composite specimens with quartz.
QUARTZ (var. ROCK CRYSTAL)
HISTORY, NAME, LOCALITIES: Rock crystal, which is common and occurs worldwide, has been collected since prehistory. Notable collecting localities are found in India, Brazil, Germany, Peru, Bolivia, Namibia, Russia, and the United States (Arkansas, Colorado, Maine, Connecticut, Virginia).
MINERALOGY, PROPERTIES, OCCURRENCE: Rock crystal is the transparent, colorless variety of macrocrystalline quartz [silicon dioxide, SiO2). The word “quartz” is believed to have originated with the Slavic kwardy, meaning “hard,” in allusion to its substantial hardness. It crystallizes in the hexagonal system and occurs mainly in hydrothermal veins, granite pegmatites, and as geode linings as short-to-long, horizontally striated, hexagonal, prismatic crystals with pyramidal terminations and distinctive, water-clear transparency. It has a Mohs hardness of 7.0, a conchoidal fracture, vitreous luster, and specific gravity of 2.65.
METAPHYSICAL PROPERTIES, LORE, USES: Rock crystal has since antiquity been one of the most widely collected of all minerals. It has served as a gemstone and ornamental stone in many cultures. Until quartz was synthesized in the 1960s, rock crystal was vital to electronic frequency controls, filters, and timing devices. Modern metaphysical practitioners call rock crystal the “universal crystal” because of its numerous abilities to sharpen insight, enhance spiritual development, improve concentration, refine focus, and energize the mind.
COLLECTORS’ INFORMATION: Rock crystal is widely collected for its brilliant transparency, superb hexagonal crystal development, and frequent occurrence on large plates and in geodes to make interesting display pieces.