Sandstone with Calcite Vein

Physical Properties

Hardness: 6-7 (sandstone matrix), 3 (calcite vein); Color: Tan/brown with white crystalline streaks; Luster: Dull/earthy for matrix, vitreous for vein; Crystal structure: Granular matrix with rhombohedral calcite crystals; Cleavage: None (matrix), perfect rhombohedral (vein).

Formation & Geological History

Formed through the accumulation and cementation of mineral grains (mostly quartz) in marine or desert environments. The white vein formed later via hydrothermal activity or groundwater precipitation, where calcium-rich water filled fractures in the rock.

Uses & Applications

Commonly used as a building material, in road construction, and for aquarium decor. Large, aesthetically pleasing specimens are used as garden stones or display pieces for collectors.

Geological Facts

Sandstone makes up about 20% of all sedimentary rocks on Earth. The white veins are often indicators of past fluid flow through a rock formation, which can be useful information for petroleum geologists.

Field Identification & Locations

Identify in the field by its gritty, sandpaper-like feel. If the white area reacts (fizzes) with diluted hydrochloric acid, it confirms the presence of calcite. Common in canyonlands and mountain ranges worldwide.

Identified on: 4/13/2026

Mode: Standard