mineral

Howlite

Howlite (Ca₂SiB₅O₉(OH)₅)

AI-generated identification · may be incorrect

Typically white to gray with dark gray spiderweb-like veining; dull to porcelain or vitreous luster and massive, fine-grained texture. Mohs hardness is about 3.5, with uneven fracture and no obvious cleavage; specific gravity is approximately 2.5–2.6.

Identified September 10, 2026More mineral →

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Physical properties

Formation & geological history

A hydrated calcium borosilicate formed in borate-rich evaporite environments, commonly as nodules in clay or limestone. It is relatively young geologically, generally Cenozoic, though exact age depends on the deposit.

Uses & applications

Used for carvings, beads, cabochons, and ornamental objects; it is often dyed blue and sold as imitation turquoise. Natural rough pieces have modest decorative and collecting value.

Geological facts

Howlite is commonly confused with turquoise because of its porous white body and webbing, and dyed specimens can closely mimic turquoise or lapis lazuli.

Field identification & locations

Identify it by its lightweight feel, soft hardness, white porous interior, and irregular gray veining; a steel knife can scratch it. Major sources include California and Nova Scotia, Canada; avoid assuming all blue material is natural turquoise.