mineral

Howlite

Howlite (Calcium borosilicate hydroxide, Ca2B5SiO9(OH)5)

Hardness: 3.5 on Mohs scale; Color: White to milky grey with dark grey or black veins; Luster: Sub-vitreous to dull; Crystal Structure: Monoclinic; Cleavage: None; Specific Gravity: 2.53-2.59

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

Identified May 25, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 3.5 on Mohs scale; Color: White to milky grey with dark grey or black veins; Luster: Sub-vitreous to dull; Crystal Structure: Monoclinic; Cleavage: None; Specific Gravity: 2.53-2.59

Formation & geological history

Formed in evaporite deposits in arid environments through the evaporation of boron-rich waters. Primarily found in sedimentary basins and often occurs in nodules that resemble cauliflower.

Uses & applications

Used primarily in jewelry as beads and carvings. It is famously used as a 'simulant' for more expensive stones like Turquoise or Lapis Lazuli because its porous nature allows it to be easily dyed. It is also a minor source of borax.

Geological facts

Howlite was first discovered in 1868 near Windsor, Nova Scotia, by Canadian geologist Henry How, who initially described it as silico-boro-calcite. It is often sold under the trade name 'White Turquoise' despite having no relation to actual turquoise.

Field identification & locations

Identify by its characteristic 'spider-web' dark veining against a white background; it can be scratched by a knife unlike quartz or turquoise. Commonly found in California and Nevada (USA), and Nova Scotia (Canada). Collectors look for large, un-dyed nodules.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

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

Green Apatite on Albite

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

mineral