Howlite, a calcium borosilicate hydroxide (Ca₂B₅SiO₉(OH)₅), is a borate mineral found in evaporite deposits. Howlite was discovered near Windsor, Nova Scotia in 1868 by Henry How (1828-1879), a Canadian chemist, geologist, and mineralogist. How was alerted to the unknown mineral by miners in a gypsum quarry, who found it to be a nuisance. He called the new mineral silico-boro-calcite; it was given the name howlite by James Dwight Dana shortly thereafter.