Sulfides - Identification and Characteristics (Key Features)

Question 1

Chalcocite

Answer 1

Tabular/pseudohexagonal crystals, Kind of graphite-like

Question 2

Cinnabar

Answer 2

Hexagonal tabular crystals, Often intergrown or penetration twins, Red streak

Question 3

Covellite

Answer 3

Rarely hexagonal tabular crystals, Dark metallic-blue to dark gray and iridescent color

Question 4

Galena

Answer 4

Perfect isometric crystals (cubes, octahedrons, or both), Steel gray streak and color

Question 5

Marcasite

Answer 5

Smells like sulfur, Pale brass-yellow to nearly white (can tarnish brown and/or iridescent), Orthorhombic and frequently coxcomb crystals

Question 6

Molybdenite

Answer 6

Thin/platy hexagonal crystals that can be easily moved and bent out of shape

Question 7

Orpiment

Answer 7

Yellow streak, Often bright yellow but can be [bright] orange-ish or brown, Often occurs with Realgar

Question 8

Pyrite

Answer 8

Black streak with greenish tinge, Metallic luster, No cleavage

Question 9

Pyrrhotite

Answer 9

Usually bronze color, Usually pseudohexagonal crystals, Magnetic (extent depends on iron deficiency, more with less iron)

Question 10

Realgar

Answer 10

Bright red color, Orange to reddish-orange streak, Prismatic and stubby crystals that are heavily striated lengthwise

Question 11

Sphalerite

Answer 11

White-brown streak (always lighter than specimen), Isometric usually twinned and tetrahedral crystals

Question 12

Stibnite

Answer 12

Metallic silver-gray color, Long slender crystals

Question 13

Arsenopyrite

Answer 13

Silver-white to steel gray-color, Distinct prismatic crystals often twinned and triangular

Question 14

Bornite

Answer 14

Copper-red to yellowish brown on fresh surface but quickly tarnishes to multicolored purple blue and red, No discernable cleavage

Question 15

Chalcopyrite

Answer 15

Brass-yellow to golden-yellow color, Tarnishes to multicolored blue purple and red, Tetragonal crystals {Looks somewhat like pyrite but won’t scratch glass}

Question 16

Enargite

Answer 16

Steel gray to black color and streak, Perfect cleavage, Prismatic and tablular crystals with flattened terminations