mineral

Howlite

Howlite — Ca₂B₅SiO₉(OH)₅

AI-generated identification · may be incorrect

White to gray, opaque, with characteristic dark gray web-like veining; matte to vitreous luster and commonly massive rather than visibly crystalline. Mohs hardness 3–3.5, poor cleavage, and specific gravity about 2.5–2.6.

Identified September 3, 2026More mineral →

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Physical properties

Formation & geological history

A borate mineral formed in evaporite deposits from boron-rich groundwater, commonly replacing limestone or accumulating in clay-rich sediments. It is geologically young to moderately old, occurring in sedimentary basins rather than a single defined age.

Uses & applications

Used for beads, carvings, cabochons, and ornamental specimens; porous material is often dyed to imitate turquoise. It has little industrial value.

Geological facts

Howlite is frequently mistaken for white turquoise, though genuine turquoise is harder and typically blue-green. Its irregular dark veining and low hardness are diagnostic clues.

Field identification & locations

Commonly found in California and Nova Scotia, Canada. Identify it by its lightweight feel, white color, gray-brown matrix-like veins, and scratchability with a steel knife; avoid destructive testing on polished pieces.