Calcite

Calcite


Composition: CaCO3
Crystal System : Trigonal
Lustre : Vitreous
Hardness : 3
Specific Gravity : 2.71

Occurrence

  • Hypogene
  • Supergene
  • Country Rock
  • 1st Oxidation Zone
  • 2nd Oxidation Zone
  • 3rd Oxidation Zone

Notable Finds

Aesthetic examples of crystallised calcite appear to have been most abundant in the second and third oxidation zones. Early collections contain notably few examples of calcite and, while this might partly reflect the collecting prejudices of the time, there is a clear implication that attractive calcite specimens were scarce in the upper levels of the mine. Collectable calcites were commonly encountered at depth, however, including the distinctive specimens from two named pockets: (1) the so-called “ice-cream pocket”, discovered in 1977 and believed to be from the second oxidation zone, comprising very pale pastel-green rhombs of calcite, but with a sugary surface texture, suggesting either a degree of recrystallisation or (more likely) a replacement of dolomite (?). (2) the so-called “crystal palace”, a very large walk-in pocket of rhombohedral calcites associated with conichalcite, discovered in 1990 on 43 Level in the third oxidation zone (Gebhard, 1999).