Ca₂B₅SiO₉(OH)₅

This sample of howlite is displayed in the Smithsonian Museum of Natural History. Howlite is a silicate mineral of boron and calcium with the composition Ca₂B₅SiO₉(OH)₅. Mindat also classifies it as a borite or a borosilicate. The samples at left are each about 10 cm across and are from Tick Canyon, California.