What is Brookite?
Brookite is one of the three principal natural polymorphs of titanium dioxide, together with rutile and anatase. Its crystals are often small but can be exceptionally sharp and lustrous.
Mineralogy and structure
Brookite has the formula TiO2 and crystallises in the orthorhombic system. Hardness is about 5.5-6 and density is around 4.1-4.2. The reference page links it with anatase and rutile as related polymorphs.
Colour and appearance
Colours range from brown and red-brown to black, yellow and sometimes metallic grey. Tabular or platy crystals with adamantine to metallic lustre are typical, often perched on quartz or albite.
Formation and localities
Brookite forms in alpine fissures, hydrothermal veins and metamorphic rocks, and may occur as a weathering product of titanium minerals. Classic sources include the Alps, Arkansas, Pakistan, Brazil, Russia and Switzerland.
Collecting and care
Sharp brookite crystals are delicate and usually small. Compare crystal habit, matrix and locality carefully because dark anatase and rutile can appear similar in photographs.
Brookite and zodiac signs
Modern crystal guides may associate Brookite with Capricorn or Aquarius because of its dark colour and connection with titanium. These associations have no mineralogical status.
Symbolic and esoteric associations
Esoteric writing may use brookite as a symbol of clarity through different structural paths, inspired by its polymorphism. It is a metaphor rather than a claim about the stone.
