mineral
Howlite
Ca2B5SiO9(OH)5 (Calcium borosilicate hydroxide)
Hardness: 3.5 on Mohs scale. Color: Milky white to ivory with grey, black, or dark brown web-like veining (matrix). Luster: Sub-vitreous, dull, or porcelain-like. Crystal System: Monoclinic.
- Hardness
- 3
- Luster
- Sub-vitreous, dull, or porcelain-like
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Physical properties
Hardness: 3.5 on Mohs scale. Color: Milky white to ivory with grey, black, or dark brown web-like veining (matrix). Luster: Sub-vitreous, dull, or porcelain-like. Crystal System: Monoclinic.
Formation & geological history
Formed in evaporite deposits in arid, lakebed environments through hydrothermal precipitation, often found as nodular or cauliflower-like masses.
Uses & applications
Widely used for fashion jewelry, ornamental carvings, and beads. Often dyed blue to imitate turquoise (sometimes marketed as 'White Turquoise' or 'Turquenite').
Geological facts
Howlite was named after Henry How, a Nova Scotian chemist, geologist, and mineralogist who discovered it in 1868. Because of its porous nature, it absorbs dye easily.
Field identification & locations
Identified by its distinctive white background with dark grey webbed matrix and soft surface that can be scratched easily by copper or iron. Commonly found in California and Nova Scotia.
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