Howlite Howlite General Category Silicate mineral Chemical formula Ca2B5SiO9(OH)5 Identification Color White to colorless Crystal habit Massive to nodular, occurs as tabular prisms flattened parallel to [100] Crystal system Monoclinic Cleavage absent Fracture conchoidal, uneven Mohs Scalehardness 3.5 Luster vitreous to dull Streak white Diaphaneity Translucent Specific gravity 2.53 - 2.59 Optical properties Biaxial (-) 2V = 73° Refractive index nα = 1.583 - 1.586 nβ = 1.596 - 1.598 nγ = 1.600 References [1][2][3] Howlite, a calcium borosilicate hydroxide (Ca2B5SiO9(OH)5), is a silicate mineral found inevaporite deposites.[4] Howlite was discovered at Tick Canyon, California in 1868 by Henry How (1828 - 1879), a Canadian chemist, geologist, and mineralogist.[1][3] In appearance, it is white with fine grey or black veins in an erratic, often web-like pattern, and is opaque with a sub-vitreous lustre. Its structure is monoclinic with a Mohs hardness of 3.5 and lacks regular cleavage. Howlite, dyed blue as a turquoise simulant Howlite is commonly used to make decorative objects such as small carvings or jewelry components. Because of its porous texture, howlite can be easily dyed to imitate other minerals, especially turquoise because of the superficial similarity of the veining patterns. The dyed howlite (or magnesite) is marketed as turquenite.[5] Howlite is also sold in its natural state, sometimes under the misleading trade names of "white turquoise" or "white buffalo turquoise", or the derived name "white buffalo stone".