mineral
Howlite
Hydrated sodium calcium borosilicate, 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 evaporate deposits in boron-rich salt marshes and lacustrine environments, primarily in Nova Scotia, California, and South Africa.
Uses & applications
Frequently used as a gemstone material, carved into decorative ornaments, or dyed blue/green to imitate turquoise.
Geological facts
Howlite is extremely porous, which makes it very easy to absorb dyes and mimic more expensive stones like turquoise.
Field identification & locations
Identified by its distinctive spiderweb matrix on a chalky white background and its softness, which allows it to be easily scratched by a copper coin.
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