mineral
Howlite
Calcium Borosilicate Hydroxide (Ca2B5SiO9(OH)5)
Hardness: 3.5 on the Mohs scale, Color: White or milky white with distinct dark grey, black, or dark brown web-like veins, Luster: Sub-vitreous to earthy, Crystal Structure: Monoclinic, Cleavage: None
- Hardness
- 3
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Physical properties
Hardness: 3.5 on the Mohs scale, Color: White or milky white with distinct dark grey, black, or dark brown web-like veins, Luster: Sub-vitreous to earthy, Crystal Structure: Monoclinic, Cleavage: None
Formation & geological history
Forms in evaporite deposits, typically in borate and calcium-rich sedimentary environments. Formed through the evaporation of saline lakes and marine basins.
Uses & applications
Commonly cut into cabochons, carved into decorative objects, or used in jewelry settings like rings and pendants. Often dyed blue or green to imitate turquoise (sometimes called turquenite).
Geological facts
Discovered in Nova Scotia in 1868 by Henry How, a Canadian chemist, geologist, and mineralogist. Because of its porous nature, it readily absorbs dyes, making it one of the most widely substituted stones for turquoise.
Field identification & locations
Identified by its distinctive white-and-grey spiderweb matrix and soft texture (can be easily scratched with a knife or copper coin). Major deposits are found in Nova Scotia, California, and South Africa.
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