mineral

Tumbled howlite (likely)

Howlite, Ca₂B₅SiO₉(OH)₅

AI-generated identification · may be incorrect

White to pale gray, opaque, with distinctive dark gray veining; typically vitreous to dull luster and massive rather than visibly crystalline. Mohs hardness 3.5, uneven fracture, and relatively low specific gravity (~2.5); the rounded shape indicates tumbling and polishing.

Identified August 10, 2026More mineral →

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Physical properties

Formation & geological history

Howlite is a borate mineral formed in evaporite-related boron-rich clay deposits, commonly as nodules or irregular masses. It is geologically young compared with many crystalline rocks, often associated with Cenozoic continental basin deposits.

Uses & applications

Used mainly for carvings, beads, cabochons, and inexpensive decorative objects; it is also commonly dyed to imitate turquoise. Not generally used as a construction stone.

Geological facts

The specimen’s appearance is consistent with howlite, though magnesite and dyed or veined marble can look similar. Howlite’s porous surface accepts dyes readily, making blue “turquenite” a common trade product.

Field identification & locations

Common localities include California and Nevada, USA, and parts of Canada and Turkey. Confirm with hardness and acid testing: it should scratch easily with a steel blade, while dilute acid may weakly react if magnesite is present.