| Answer | Crossword Clue |
|---|---|
| marcasite | sulphide of iron in orthorhombic crystals |
| marcasites | MARCASITE, sulphide of iron in orthorhombic crystals |
| tetrahedrite | native sulphide of antimony, iron, and copper, forming a series with tennantite and typically occurring as tetrahedral crystals |
| tetrahedrites | TETRAHEDRITE, native sulphide of antimony, iron, and copper, forming a series with tennantite and typically occurring as tetrahedral crystals |
| bismuthinite | a grey mineral consisting of bismuth sulphide in orthorhombic crystalline form |
| bismuthinites | BISMUTHINITE, a grey mineral consisting of bismuth sulphide in orthorhombic crystalline form |
