mineral

Botryoidal calcite cluster

Calcite (CaCO₃), likely iron-stained; possibly associated with aragonite or quartz

AI-generated identification · may be incorrect

White to cream, lumpy/botryoidal crystals with brown iron-oxide staining and a vitreous to pearly luster. Calcite has Mohs hardness 3, rhombohedral cleavage, non-cubic crystals, and specific gravity about 2.71; it effervesces strongly in dilute hydrochloric acid.

Identified August 15, 2026More mineral →

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Physical properties

Formation & geological history

Forms when calcium-rich groundwater precipitates carbonate in cavities, veins, caves, or hydrothermal environments; iron-bearing fluids create the brown staining. The specimen’s exact geological age cannot be determined from the image.

Uses & applications

Common calcite is used in cement, lime, aggregate, fillers, and optical applications; attractive clusters are collected as mineral specimens. It is generally unsuitable for durable jewelry because of its softness and cleavage.

Geological facts

Calcite is one of the most abundant carbonate minerals and has strong birefringence, producing double images through clear crystals. Brown coloration commonly comes from limonite or hematite coatings.

Field identification & locations

Look for rhombohedral cleavage, relatively soft surfaces, and vigorous acid fizzing; calcite is common worldwide, including Mexico, the United States, Iceland, and China. The image alone cannot exclude a related carbonate mineral such as aragonite.