From YPPedia

Chalcocite
Raw goods
Mass: 5.7 kg	Volume: 1 L
Obtained from: Merchant Brigands, Commodities markets
Used by: Furnishers, Iron mongers, Shipyards, Weaveries
End products: Bludgeons, Cloth, Furniture, Swords

Chalcocite is one of eleven minerals. It is an ingredient in furniture, cloth, swords, and the bludgeon leather gloves.

German article: Chalcocit

Spawn Locations

Cobalt	Hunter	Ice	Malachite	Midnight	Sage	Viridian
Moab Island*	Ix Chel* Marlowe Island	Cringe Island*	Murex Island* Striga Cay* Tethys Island*	Cleopatra's Pearls Lynx Island* Wrasse Island	Ambush Island	Moab Island

*Islands without market bidding.

Use

Chalcocite is needed in the production of:

Furnisher products

Armor with spear (1) Armor with sword (1) Blue urn (2) Crossed swords (6)

Gibbet (3) Pile of bones (3) Skeleton chair (3) Skeleton in Shackles (3)

Skeleton table (3) Tombstone (1) Yellow urn (2)

Iron monger products

Short sword (1)

Saber (3)

Skull dagger (3)

Shipyard products

Leather Gloves (3)

Weavery products

Grey cloth (1) Light green cloth (1)

Fine grey cloth (2)

Fine light green cloth (2)

Real World Counterpart

Chalcocite is made from the elements Copper and Sulfur, by the chemical formula Cu₂S. This is based on the data from http://webminerals.com