s
Russian Gemstones Encyclopedia

Vladimir Bukanov. Russian Gemstones Encyclopedia

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

HOWLITE


HOWLITE (Howlith—Howlite—√овлит) (How, H. 1868), after Henry How (1828-1879), Professor of chemistry and Nat. Hist., King’s College, Windsor, Nova Scotia, who first described the mineral. Silicate – Ca2[B3O4(OH)2•OSiB2O4(OH)3], subclass of chain silicate, monoclinic system. Hardness 3-4. Density 2.5. Dull luster. Viscous. Howlite is found in the form of typical concretions, which look like cauliflower. These concretions display twisted-fibrous structure, which provides high viscosity of the material with low hardness. Color: snow-white to pale blue. Non-transparent to translucent because of numerous inclusions. In the U.S.A., howlite was found in the south of California in the form of veins and concretions up to 30 cm. in cross-section at the borate deposits Lang and Govern Gulch. Concretions can be run through with black veins, which make howlite resembling one of the varieties of turquoise. In Canada, such concretions, mainly small ones, are found at the gypsum and anhydrite deposits Windsor and Wentworth, Nova Scotia.
Howlite is a popular ornamental stone. Because of its high porosity, it can be easily colored. In the tumbled form or in cabochons it is used for the imitation of turquoise.
Search