21 Photos
Greenockite
Chemical Formula	CdS
Species	Sulfides
Crystal System	Hexagonal
Mohs Scale	3
Specific Gravity	4.8-4.9
Color	Honey yellow, citron yellow, orange yellow
Streak	Yellow orange to brick red
Luster	Adamantine, Resinous
Refractive Index	n = 2.529 n = 2.506
Diaphaneity	Translucent
Cleavage	Distinct/GoodDistinct on , imperfect on .
Fracture	Conchoidal
Crystal Habit：Colloform - forming from a gel or colloidal mass; encrustations - forms crust-like aggregates on matrix; radial - crystals radiate from a center without producing stellar forms (e.g. stibnite)
Geological Setting：An uncommon mineral of sulfide deposits.

Greenockite is a rare cadmium mineral that consists of cadmium sulfide, CdS, in crystalline form. Greenockite crystallizes in the hexagonal system. It occurs as massive encrustations and as six-sided pyramidal crystals which vary in color from a honey yellow through shades of red to brown. The Mohs hardness is 3 to 3.5 and the specific gravity is 4.8 to 4.9.

Greenockite occurs with other sulfide minerals such as sphalerite and galena. It is the only ore mineral of cadmium, most cadmium is recovered as a byproduct of zinc and lead mining.

It was first recognized in 1840 in Bishopton, Scotland, during the cutting of a tunnel for the Glasgow, Paisley and Greenock Railway. The mineral was named after the land owner Lord Greenock. It is also known from the lead-zinc districts of the central United States.