Green Calcite Crystal

A massive green calcite crystal from the USA, with an apple-green hue that is considered a rare shade in carbonate mineralogy. The heavy specimen exhibits the typical trigonal scalenohedral form with clear longitudinal striations along the crystal axes.

Calcite is calcium carbonate (CaCO₃) and crystallizes trigonally in more habit variations than almost any other mineral. The green coloration is caused by traces of divalent iron or manganese in a rare constellation; most calcites are colorless to yellowish.

With a Mohs hardness of 3, calcite is one of the softer minerals and reacts sensitively to acid. A drop of vinegar produces characteristic effervescence, a classic identification method in mineralogical fieldwork.

US green calcites typically originate from deposits in Mexico or the southern USA, where carbonate voids were permeated with iron-bearing solutions. Crystals of this size and purity are rare and are usually removed early from the exploration hub.

A collector's item with carbonate-specific color characteristics, suitable for collectors documenting the spectrum of calcite varieties.