mineral
Howlite
Howlite (Ca2B5SiO9(OH)5)
Hardness: 3.5 on the Mohs scale. Color: Opaque white to ivory with fine dark gray or black web-like veins (matrix). Luster: Sub-vitreous to dull, porcelain-like. Crystal structure: Monoclinic.
- Hardness
- 3
- Luster
- Sub-vitreous to dull, porcelain-like
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Physical properties
Hardness: 3.5 on the Mohs scale. Color: Opaque white to ivory with fine dark gray or black web-like veins (matrix). Luster: Sub-vitreous to dull, porcelain-like. Crystal structure: Monoclinic.
Formation & geological history
Forms in evaporite deposits, usually as nodular masses in arid basins or ancient lake environments rich in borates. Major deposits are found in Canada (Nova Scotia) and the southwestern USA (California).
Uses & applications
Popular for lapidary work, decorative carvings, beads, and jewelry pendants. Because of its porous nature, howlite is frequently dyed to imitate turquoise (sometimes called 'turquenite').
Geological facts
Howlite was first discovered in 1868 near Windsor, Nova Scotia, by Henry How, a Canadian chemist, geologist, and mineralogist, after whom it was named.
Field identification & locations
Identified by its distinctive white porcelain appearance intersected by fine gray to black veining. It is relatively soft and easily scratched by steel or copper compared to turquoise.
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