Where is Calcite with Pyrite found?

Calcite with Pyrite occurs in specific geological environments. Knowing where to look, and in what kind of rock, is the difference between going home empty-handed and finding a great specimen.

Where to find Calcite with Pyrite

Collecting tips

1. Look for Hydrothermal Veins. These are common environments for both minerals to crystallize together. Look for veins cutting through other rock types.
2. Examine Sedimentary Rocks. Especially shales and limestones, where pyrite can form concretions or disseminated crystals within a calcite-rich matrix under anoxic conditions.
3. Check Mine Dumps. Old mine dumps from lead-zinc, copper, or gold mines often contain gangue minerals like calcite and pyrite.
4. Use a Hand Lens. To distinguish the metallic luster and crystal forms of pyrite from the vitreous luster and rhombohedral cleavage of calcite.
5. Acid Test for Calcite. Calcite will effervesce vigorously with dilute hydrochloric acid (HCl), which can help confirm its presence and distinguish it from other carbonates like dolomite (which reacts slowly or not at all with cold dilute HCl).

Quick Check

Color:

Calcite: Variable (white, colorless, etc.); Pyrite: Brass-yellow.

Luster:

Calcite: Vitreous; Pyrite: Metallic.

Streak:

Calcite: White; Pyrite: Greenish-black to brownish-black.

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