mineral
Howlite
Calcium Borosilicate Hydroxide (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
Forms as irregular nodules in evaporite deposits, primarily created through the precipitation in boron-rich saline lakes.
Uses & applications
Widely used in ornamental carvings, beads, and polished jewelry, often dyed blue to imitate turquoise.
Geological facts
Howlite is porous and absorbs dyes exceptionally well, making it a common substitute for more expensive turquoise or jasper.
Field identification & locations
Identified by its distinctive spiderweb matrix on a chalky white background and its softness, easily scratched with a knife.
