mineral

Howlite

Howlite, Ca₂B₅SiO₉(OH)₅

AI-generated identification · may be incorrect

White to creamy, opaque, with distinctive gray-black spiderweb veining; hardness about 3.5 Mohs, vitreous to dull luster, irregular fracture, and no prominent cleavage. The specimen is polished and tumbled, giving it a smooth surface.

Identified August 11, 2026More mineral →

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Physical properties

Formation & geological history

Howlite is a borate mineral formed in evaporite environments, commonly as nodules or masses in boron-rich lake sediments. It is geologically young relative to many crystalline rocks, often associated with Miocene to Quaternary deposits.

Uses & applications

Used mainly for beads, cabochons, carvings, and ornamental stones; it is also commonly dyed blue and sold as imitation turquoise. It has little industrial importance.

Geological facts

Howlite is often mistaken for turquoise because it accepts dyes readily and can resemble turquoise when blue-colored. Its natural gray veining and relatively low hardness help distinguish it from true turquoise.

Field identification & locations

Common localities include California and Nevada, USA, and parts of Canada. Identify it by its white color, web-like gray veining, low hardness, and lack of turquoise’s blue-green natural color; avoid confusing it with magnesite.