Cylindrite

Formula:  Pb₄FeSn₄Sb₂S₁₆

Origin of name:  From Greek for roll, in allusion to its typical habit

Crystal system:  Triclinic

Crystal class:  -1

Twinning:

Unit cell: a = 11.773 Å, b = 5.790 Å, c = 5.810 Å, α = 90°, β = 92.38°, g = 93.87° (pseudotetragonal)

              a = 11.709 Å, b = 3.670 Å, c = 6.320 Å, α = 90°, β = 92.58°, g = 90.85° (pseudohexagonal)

Colour:  Blackish lead-gray

Diaphaneity:  Opaque

Luster:  Metallic

Habit:  Cylindrical forms in masses; spherically grouped aggregates

Hardness:  2.5

Specific gravity:  5.46

Cleavage:  None

Tenacity: Slightly malleable

Streak:  Black

Synonyms/varieties:

Comments: Found in tin-bearing deposit