mineral
White Howlite (likely)
Howlite, Ca₂B₅SiO₉(OH)₅
AI-generated identification · may be incorrectA 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.
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Physical properties
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.
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.
