mineral

White Howlite (likely)

Howlite, Ca₂B₅SiO₉(OH)₅

AI-generated identification · may be incorrect

A white, opaque, polished/tumbled stone with gray-black spiderweb veining and a dull to waxy luster. Mohs hardness 3.5; monoclinic crystal system, commonly massive rather than visibly crystalline; specific gravity about 2.5–2.6.

Identified September 2, 2026More mineral →

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Physical properties

Formation & geological history

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

Uses & applications

Used for beads, cabochons, carvings, and decorative objects; its porous white material is often dyed to imitate turquoise. It has little industrial importance.

Geological facts

The distinctive gray veining resembles turquoise matrix, making howlite a frequent turquoise substitute. Similar-looking material may be magnesite, which is also commonly dyed.

Field identification & locations

Identify it by its very low hardness, lightweight feel, white color, and irregular gray veining; it can be scratched by a steel knife, though testing may damage it. Major sources include California and Nova Scotia, Canada.