mineral
Howlite
Howlite (Ca2B5SiO9(OH)5)
AI-generated identification · may be incorrectMohs hardness of 3.5, white or milky color with dark grey or black web-like veins, sub-vitreous to earthy luster, and monoclinic crystal system.
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Physical properties
Mohs hardness of 3.5, white or milky color with dark grey or black web-like veins, sub-vitreous to earthy luster, and monoclinic crystal system.
Formation & geological history
Formed as borate minerals in evaporite deposits, typically in arid environments via the alteration of gypsum or anhydrite.
Uses & applications
Widely used in ornamental carvings, beads, and polished worry stones, and frequently dyed blue to imitate turquoise.
Geological facts
Discovered in Nova Scotia in 1868 by Henry How, a Canadian chemist and geologist, it is porous and readily absorbs dyes.
Field identification & locations
Easily identified by its characteristic web-like matrix patterns on a chalky white background and its softness, which allows it to be easily scratched by a knife.
