Willemite
Chemical Formula	Zn2SiO4
Species	Silicates
Crystal System	Trigonal
Mohs Scale	5
Specific Gravity	3.9-4.2
Color	Colorless to white, gray, flesh-red, dark brown, honey-yellow, apple-green, blue
Streak	White
Luster	Vitreous, Resinous
Refractive Index	n = 1.691 - 1.694 n = 1.719 - 1.725
Diaphaneity	Transparent, Translucent
Cleavage	Distinct/GoodGood to poor , poor
Fracture	Irregular/Uneven, Sub-Conchoidal
Crystal Habit：Fibrous, botryoidal to massive
Geological Setting：Occurs generally as a secondary zinc mineral derived from the supergene weathering of sphalerite (gossan & other oxidized deposits) or by the alteration of primary sphalerite in hydrothermal veins. The Franklin-Sterling Hill orebodies are unique in the context of massive willemite as a primary ore mineral, derived from an unknown proto-ore during Cambrian, or older, times.