mineral

Howlite

Calcium borosilicate hydroxide (Ca2B5SiO9(OH)5)

Hardness: 3.5 on Mohs scale; Color: White or milky grey with dark grey or black veining; Luster: Sub-vitreous to pearly; Crystal structure: Monoclinic; Cleavage: None visible in massive form; Specific gravity: 2.53-2.59

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

Identified June 28, 2026More mineral →

Explore Howlite in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Formation & geological history

Formed in evaporite deposits, typically in arid environments where boron-rich waters have concentrated. It is found in nodular masses rather than distinct crystals.

Uses & applications

Commonly used for ornamental carvings, decorative objects, and jewelry. It is highly porous and frequently dyed blue to imitate turquoise or red to imitate coral.

Geological facts

Howlite was first discovered by Henry How in 1868 in Nova Scotia, Canada. It is often sold under trade names like 'White Turquoise' or 'Buffalo Turquoise,' even though it is not related to turquoise mineralogically.

Field identification & locations

Identify by its characteristic 'spider web' veining and chalky white base. It can be scratched by a copper penny but not by a fingernail. Commonly found in California and Nova Scotia.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

Epidote

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

metamorphic

Gypsum (variety Selenite or Alabaster)

Calcium sulfate dihydrate (CaSO4·2H2O)

Mineral

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

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

Metamorphic Rock