mineral

Howlite

Howlite, Ca₂B₅SiO₉(OH)₅

AI-generated identification · may be incorrect

White to gray, opaque, porcelain-like mineral with dark gray spiderweb veining; Mohs hardness 3.5, vitreous to dull luster, monoclinic crystal structure, and uneven fracture. The pictured piece appears polished or tumbled.

Identified August 17, 2026More mineral →

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Physical properties

Formation & geological history

Howlite forms as a borate mineral in evaporite deposits, commonly as nodules in arid sedimentary environments. It is geologically young relative to many crystalline rocks, typically associated with Cenozoic borate basins.

Uses & applications

Used primarily for beads, cabochons, carvings, and decorative objects; it is also commonly dyed to imitate turquoise. It has little industrial value.

Geological facts

Howlite is frequently confused with turquoise, but it is softer, usually whiter, and has a more irregular gray web pattern. Some marketed “white turquoise” is actually undyed or dyed howlite.

Field identification & locations

Common localities include California and Nevada, USA, and parts of Canada and Mexico. Identify it by its low hardness, white color, black-gray veining, and ability to be scratched by a steel knife; vinegar does not significantly react.