Sulfides: Pentlandite

Composition: (Fe,Ni)₉S₈; cobalt may substitute for iron and nickel

Crystal system:: Isometric; typically massive

7.8.1
massive pentlandite
Kambalda WA Australia

Properties:

• Metallic lustre
• Bronze-yellow color
• Bronze-yellow streak
• Knife scratches easily (Mohs Hardness 3.5-4)
• High density
• No cleavage; may show an octahedral parting
• Uneven fracture
• Not ferromagnetic but usually associated with pyrrhotite which is variably ferromagnetic.
• Does not react with hydrochloric acid (HCl)

Occurrence:

Pentlandite occurs with other sulfides, particularly pyrrhotite and chalcopyrite in massive segregations in mafic igneous rocks.

7.8.2
massive pentlandite
Kambalda WA Australia

Nickel and ferronickel are produced from smelting of pentlandite-pyrrhotite ores.