Howlite
Howlite · Decorative Stone and Semi-Precious Collector Mineral
Crystal System
Monoclinic; typically occurs as massive nodules, tabular crystals are extremely rare.
Mineral Group
Borates
Chemical Formula
Ca2Si5B5O9(OH)5
Formation Process
Forms as borate minerals in evaporite deposits, typically in desert or arid environments where boron-rich saline lakes evaporate over time.
About This Crystal
The specimen is a small, polished, tumbled rectangular stone of opaque chalky white color, heavily webbed with fine, dark grey to black veins in an irregular matrix pattern, giving it a distinctive spider-web appearance.
Physical Characteristics
Color is white or milky-white with dark grey or black veining; streak is white; cleavage is none distinct; fracture is subconchoidal to uneven; specific gravity is approximately 2.53 to 2.59; tenacity is brittle.
Optical Properties
Biaxial (+) with refractive indices of nα = 1.583, nβ = 1.589, nγ = 1.605; birefringence is 0.022; it is translucent to opaque with a sub-vitreous to porcelain-like luster.
Hardness & Durability
Origin Region
Primarily found in Nova Scotia, Canada, as well as California and Nevada in the USA, and South Africa.
Hardness & Durability
Mohs hardness of 3.5, making it quite soft and easily scratched by a copper coin or knife. It has low durability and requires careful wear when used in jewelry.
Care & Maintenance
Clean with warm, soapy water and a soft cloth. Avoid harsh chemical cleaners, prolonged exposure to moisture, and ultrasonic cleaners. Store separately from harder gemstones to prevent scratching.
Rarity & Value
Common and widely available; relatively inexpensive, often sold in tumbled form or used as an affordable imitation for turquoise when dyed blue.
Special Characteristics
Porous structure allows it to absorb dyes easily, which is why it is frequently treated and dyed to mimic turquoise (often called 'turquenite') or red coral.
Lore & History
Discovered in Nova Scotia in 1868 by Henry How, a Canadian chemist and geologist. In metaphysical traditions, howlite is considered a stone of ultimate calm, widely used for relieving stress, reducing anger, and aiding with insomnia.