mineral
Howlite
Calcium Borosilicate Hydroxide (Ca2B5SiO9(OH)5)
AI-generated identification · may be incorrectMohs hardness 3.5, opaque white or milky color with dark grey or black web-like veins, subvitreous to earthy luster, monoclinic crystal system.
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Physical properties
Mohs hardness 3.5, opaque white or milky color with dark grey or black web-like veins, subvitreous to earthy luster, monoclinic crystal system.
Formation & geological history
Forms in borate deposits within evaporite basins through the precipitation of boron-rich minerals in arid environments.
Uses & applications
Commonly used for ornamental carvings, beads, and cabochons, and frequently dyed blue or green to imitate turquoise.
Geological facts
Howlite was discovered in Nova Scotia in 1868 by Canadian chemist Henry How, who initially named it silicoborocalcite.
Field identification & locations
Identified by its characteristic web-like matrix, white color, and softness that allows it to be easily scratched by a knife or copper coin. Found primarily in Nova Scotia and California.
