Yellow Calcite

Physical Properties

Hardness: 3 on Mohs scale; Color: Honey yellow to bright yellow; Luster: Vitreous to waxy; Crystal Structure: Trigonal/Rhombohedral; Cleavage: Perfect rhombohedral in three directions; Specific Gravity: 2.71

Formation & Geological History

Formed through sedimentary processes, particularly by chemical precipitation from calcium-rich solutions or as a secondary mineral in igneous hydrothermal veins. It can occur in a wide variety of geological ages and environments, from marine settings to cave deposits.

Uses & Applications

Used primarily as a decorative stone, for lapidary work (cabochons, carvings), and as a specimen for mineral collectors. In industrial form, calcite is used in cement, fertilizers, and the chemical industry.

Geological Facts

Calcite exhibits double refraction (birefringence), where a single beam of light entering the crystal is split into two. It is also highly reactive to dilute hydrochloric acid, which causes it to effervesce or fizz.

Field Identification & Locations

Identify in the field by its distinctive rhombohedral cleavage (it breaks into tilted cubes/blocks) and its softness (can be scratched by a copper penny). It is commonly found in limestone-rich areas globally, with notable deposits in Mexico, Brazil, and the USA (Tennessee/Illinois).

Identified on: 4/23/2026

Mode: Standard