mineral

Howlite

Calcium borosilicate hydroxide (Ca2B5SiO9(OH))

Hardness: 3.5 (Mohs scale); Color: Chalky white with dark grey/black irregular veins (dendritic); Luster: Sub-vitreous to earthy; Crystal Structure: Monoclinic (usually found in nodules); Specific Gravity: 2.53-2.59

Hardness: 3
Luster: Sub-vitreous to earthy

Identified June 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed in evaporite deposits in arid environments (typically as nodules in gypsum or clay beds). Primarily found in continental basins where borate-rich waters evaporated.

Uses & applications

Primarily used as a decorative stone in jewelry (beads, cabochons) and as a carvings. Often used as an imitation stone because its porous nature allows it to be dyed to look like turquoise or coral.

Geological facts

Howlite was first discovered in 1868 near Windsor, Nova Scotia, by Henry How, an influential Canadian chemist and geologist. It is often sold as 'White Turquoise' or 'Buffalo Turquoise' in the jewelry market.

Field identification & locations

Identify by its distinctive spider-web veining and chalky white color. It is found in abundance in Tick Canyon, California, Cape Breton, Nova Scotia, and parts of Turkey and Germany.

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Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

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mineral