Sandstone (Micaceous Sandstone)

Physical Properties

Hardness: 6-7 (Mohs scale) for quartz grains; Color: Tan, brown, or yellowish with golden-glittering mica flakes; Luster: Pearly or metallic on flakes, earthy on matrix; Structure: Clastic, bedded fabric; Cleavage: None for rock, basal for mica flakes.

Formation & Geological History

Formed by the accumulation and cementation of sand-sized mineral grains or rock fragments, often in riverbeds, deltas, or desert environments. The mica flakes represent weathered bits of metamorphic or igneous rocks transported and deposited during sedimentation.

Uses & Applications

Used primarily as building stone, pavers, and decorative landscaping. Micaceous varieties are sometimes sought after for their aesthetic 'sparkle' in ornamental garden paths or architectural cladding.

Geological Facts

The 'gold' glitter seen in the image is often mistaken for real gold or fool's gold (pyrite), but it is actually Muscovite or Phlogopite mica which reflects light at specific angles.

Field Identification & Locations

Identify in the field by its gritty texture (feels like sandpaper) and the presence of flat, reflective flakes that disappear when the rock is tilted. Found globally in sedimentary basins.

Identified on: 4/17/2026

Mode: Standard