Howlite
Howlite · Decorative Stone and Semi-Precious Mineral Specimen
Crystal System
Monoclinic; typically occurs as massive nodules, tuberous masses, or microcrystalline aggregates rather than distinct visible crystals.
Mineral Group
Borates
Chemical Formula
Ca2B5SiO9(OH)5
Formation Process
Sedimentary, formed as borate minerals precipitate in evaporating saline lake environments and boron-rich basins.
About This Crystal
An opaque, chalky to milky white tumbled stone featuring a distinctive web of dark grey to black matrix veins that create a spiderweb or marble-like pattern across the surface. It has a smooth, polished texture with a sub-vitreous to porcelain-like luster.
Physical Characteristics
Color is white to milky white with grey or black veining; 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; often exhibits a faint yellow or orange fluorescence under ultraviolet light.
Optical Properties
Biaxial positive with refractive indices around 1.583 to 1.605; birefringence is low (up to 0.022); pleochroism is absent due to its opaque to sub-translucent nature and microcrystalline structure.
Hardness & Durability
Origin Region
Major deposits are located in Nova Scotia (Canada), California (USA), South Africa, and Germany. It typically forms in evaporite deposits.
Hardness & Durability
Mohs hardness is 3.5, making it quite soft and easily scratched by a knife or quartz. It has poor durability for everyday rings or bracelets, requiring protective settings, and is vulnerable to acids.
Care & Maintenance
Clean gently with warm, soapy water and a soft cloth. Avoid ultrasonic cleaners, steam cleaners, harsh chemicals, and prolonged exposure to acids. Store separately from harder gemstones to prevent scratching.
Rarity & Value
Common and widely available. Value is very low, making tumbled stones and cabochons highly affordable. Frequently dyed blue to imitate turquoise (often sold as 'turquenite').
Special Characteristics
Porous structure which readily absorbs dyes, making it commonly treated to mimic more expensive turquoise or red coral. Exhibits a smooth, porcelain-like touch when polished.
Lore & History
Discovered in Nova Scotia in 1868 by Henry How, a Canadian chemist and mineralogist. In crystal healing lore, howlite is considered an extremely calming stone, associated with reducing stress, anxiety, and anger, and is often linked to the crown chakra.