mineral

Howlite

Calcium borosilicate hydroxide (Ca2B5SiO9(OH)5)

Hardness: 3.5 on Mohs scale; Color: Milky white to grey with dark grey or black veins; Luster: Sub-vitreous to dull; Crystal structure: Monoclinic; Cleavage: None visible in hand specimens; Specific gravity: 2.53-2.59.

Hardness: 3
Color: Milky white to grey with dark grey or black veins
Luster: Sub-vitreous to dull

Identified May 31, 2026More mineral →

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Physical properties

Formation & geological history

Howlite is typically formed in evaporite deposits in arid environments through the evaporation of alkaline waters containing boron and silica. It is often found in massive nodules.

Uses & applications

Used primarily for decorative carvings, sculptures, and jewelry. It is a popular 'imitation' stone because its porous nature allows it to be dyed blue to mimic turquoise or red to mimic coral.

Geological facts

Named after Henry How, the Canadian mineralogist who first described it in 1868. In its natural white state, it is sometimes marketed as 'White Turquoise' or 'White Buffalo Stone', although it is not related to turquoise.

Field identification & locations

Identify by its white, porcelain-like appearance with erratic grey web-like veining. It is much softer than quartz or turquoise and can be scratched by a copper penny or steel blade. Commonly found in Nova Scotia, Canada, and various locations in California and Nevada, USA.

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

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

Metamorphic Rock

Biotite Schist

Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]

metamorphic