mineral
Howlite
Calcium Borosilicate Hydroxide (Ca2Si4O10(OH)2·B(OH)3)
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
Forms in evaporite deposits, typically in boron-rich salt marshes and lacustrine environments through chemical precipitation.
Uses & applications
Commonly used for ornamental carvings, beads, and cabochons, often dyed blue to imitate turquoise.
Geological facts
Howlite is extremely porous, which makes it very receptive to dyes used by lapidaries to simulate more expensive gemstones.
Field identification & locations
Easily identified by its soft feel, chalky white matrix, and characteristic dark veining. Found notably in Nova Scotia, California, and South Africa.
