Howlite
Howlite · Semi-Precious Gemstone and Decorative Stone
Crystal System
Monoclinic; typically occurs as massive, compact nodules, or in a microcrystalline or chalky habit, rarely forming distinct prismatic crystals.
Mineral Group
Borates
Chemical Formula
Ca2B5SiO9(OH)5
Formation Process
Sedimentary formation, specifically as evaporite deposits in boron-rich salt lakes and lacustrine environments under arid or semi-arid conditions.
About This Crystal
The specimen is a tumbled and polished piece of howlite, featuring a smooth, curved shape. It displays an opaque, milky white to chalky off-white body color characterized by a fine, web-like network of dark grey to black matrix veins weaving through the stone, giving it a marble-like appearance. The polish is smooth and waxy.
Physical Characteristics
Color is white or milky grey with dark grey or black veins. Streak is white. Cleavage is none distinct. Fracture is sub-conchoidal to uneven. Specific gravity is approximately 2.53 to 2.59. Tenacity is brittle. It often shows a faint yellow or orange-white fluorescence under ultraviolet light.
Optical Properties
Biaxial (+) with refractive indices of nalpha = 1.583, nbeta = 1.586, and ngamma = 1.605. It is doubly refractive with low birefringence and is non-pleochroic. It presents an opaque to sub-translucent appearance with a vitreous to sub-vitreous or sub-resinous luster on unpolished surfaces, becoming waxy when polished.
Hardness & Durability
Origin Region
Nova Scotia, Canada, as well as California, Nevada, and parts of South Africa and Germany. It typically forms in evaporite deposits.
Hardness & Durability
Mohs hardness of 3.5, making it quite soft and easily scratched by a copper penny or steel knife. It has low durability and poor wearability for high-impact jewelry like rings or bracelets unless securely set.
Care & Maintenance
Clean gently with warm, soapy water and a soft cloth. Avoid ultrasonic and steam cleaners, as well as harsh chemical detergents and prolonged exposure to acids. Store separately in a soft pouch to prevent scratching from harder stones.
Rarity & Value
Common and widely available. Value is generally low, making tumbled stones and polished cabochons very affordable. Because of its porous nature, it is frequently dyed blue or green to imitate turquoise (often sold as 'turquenite' or 'white turquoise').
Special Characteristics
Highly porous structure which readily absorbs dyes, and its characteristic dark matrix webbing that closely mimics turquoise or white marble.
Lore & History
Named after Henry How, a Canadian chemist and geologist who first discovered it in Nova Scotia in 1868. In metaphysical practices, howlite is considered a stone of ultimate calm, patience, and stress relief, frequently associated with the crown chakra and used to quiet an overactive mind and aid in sleep.