• Chemistry: Pb9As4S15, Lead Arsenic Sulfide
  • Class: Sulfides
  • Subclass: Sulfosalts
  • Uses: Mineral specimens and as a very minor ore of lead.
  • Specimens

Gratonite is a rare lead sulfide mineral. It forms nice crystals that can be arranged into rosette-like clusters with projecting rhombohedral terminations. Clusters can be attractive and good specimens command large prices, mostly because of the rarity of the mineral. Gratonite is a sulfosalt, a segment of sulfides where the arsenic acts more like a metal than a non-metal and occupies a position where it is bonded to sulfurs.

Also, Gratonite is the most common mineral whose symmetry is in the Trigonal Pyramidal Class


  • Color is a dark lead gray.
  • Luster is metallic.
  • Transparency: Crystals are opaque.
  • Crystal System: Trigonal; 3
  • Crystal Habits include rhombohedral as well as hexagonal prismatic crystals capped by three rhombohedral faces. Clusters can be found in rosette-like aggregates, also massive.
  • Cleavage: None.
  • Fracture: Subconchoidal.
  • Hardness is 2.5
  • Specific Gravity is 6.2 (heavier than average for metallic minerals)
  • Streak is gray.
  • Notable Occurrences are limited to the Excelsior Mine, Cerro de Pasco, Peru.
  • Best Field Indicators are crystal habit, locality, color and density.
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Available GRATONITE specimens:
see this List of ALL specimens including SOLD ones


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