mineral

Howlite

Calcium borosilicate hydroxide (Ca2B5SiO9(OH)5)

Hardness: 3.5 on Mohs scale; Color: Milky white to grey with black/brown veining; Luster: Sub-vitreous, dull; Crystal structure: Monoclinic; Cleavage: None (conchoidal fracture); Specific gravity: 2.53–2.59

Hardness: 3
Color: Milky white to grey with black/brown veining
Luster: Sub-vitreous, dull

Identified April 15, 2026More mineral →

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Physical properties

Formation & geological history

Formed in evaporite deposits where borate-rich liquids have pooled and evaporated. Often found in cauliflower-like nodules. Typically found in sedimentary environments.

Uses & applications

Commonly used for lapidary work, decorative carvings, and beads for jewelry. Due to its porous nature, it is frequently dyed blue or green to imitate turquoise.

Geological facts

Howlite was first discovered in 1868 near Windsor, Nova Scotia, by Henry How, a Canadian mineralogist. It is often sold as 'White Turquoise' even though it is unrelated to actual turquoise chemically.

Field identification & locations

Identify by its 'spider-web' grey veins and softness (it can be scratched by a steel nail). Commonly found in Tick Canyon, California, and various sites in Nova Scotia.

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

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral