Orange Calcite with Siderite/Iron Oxide Coating

Physical Properties

Hardness: 3 (Mohs scale), Color: Amber/Orange due to iron inclusions, Luster: Vitreous to pearly, Crystal structure: Trigonal/Rhombohedral, Cleavage: Perfect rhombohedral in three directions, Specific gravity: 2.71

Formation & Geological History

Formed through chemical precipitation from calcium-rich solutions in sedimentary environments or hydrothermal veins. The orange coloration generally comes from the presence of iron oxide (limonite or hematite) during or after crystal growth.

Uses & Applications

Primary use is for mineral collecting and metaphysical/spiritual purposes. Industrial calcite is used in cement, fertilizers, and as an acid neutralizer.

Geological Facts

Calcite is one of the most common minerals on Earth, but large crystal clusters like this are prized by collectors. It is chemically identical to limestone and marble, but in a crystallized form.

Field Identification & Locations

Identify in the field by its rhombohedral crystal shape and its reaction (fizzing) when exposed to dilute hydrochloric acid or strong vinegar. Commonly found in limestone quarries or metal ore veins.

Identified on: 4/16/2026

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