Rock Identifier
Sandstone with Foliose Lichen (Arenite (Rock matrix) with Xanthoparmelia or Flavoparmelia (Lichen genus)) — sedimentary
sedimentary

Sandstone with Foliose Lichen

Arenite (Rock matrix) with Xanthoparmelia or Flavoparmelia (Lichen genus)

Hardness: 6-7 (quartz-rich sand); Color: reddish-brown to tan; Luster: earthy/dull; Structure: clastic/granular with distinct horizontal bedding planes; Specific gravity: approx 2.2-2.8.

Hardness
6-7 (quartz-rich sand)
Color
reddish-brown to tan
Luster
earthy/dull
Identified More sedimentary

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Physical properties

Hardness: 6-7 (quartz-rich sand); Color: reddish-brown to tan; Luster: earthy/dull; Structure: clastic/granular with distinct horizontal bedding planes; Specific gravity: approx 2.2-2.8.

Formation & geological history

Formed from the accumulation and lithification of sand-sized mineral particles or rock fragments. The reddish hue indicates oxidation (iron oxide) often found in terrestrial or desert environments; most specimens are Palaeozoic to Mesozoic in age.

Uses & applications

Construction (cut stone), ornamental stone for landscaping, and as an aquifer in geology. The lichen on it is primarily of biological/botanical interest rather than industrial.

Geological facts

Sandstone makes up about 10-20% of Earth's sedimentary rocks. The growth of lichen on the surface is a form of biological weathering, as lichen acids slowly break down the mineral bonds.

Field identification & locations

Identify by its gritty texture (feels like sandpaper) and visible layers or 'bedding.' Commonly found in canyons, dry river beds, and coastal cliffs worldwide. Collectors value pieces with unique weathering patterns or biological inclusions like these lichens.