sedimentary
Sandstone (likely Graywacke or Arkose)
Clastic Sedimentary Rock (primarily SiO2 with various lithic fragments)
Hardness: 6-7 Mohs; Color: Gray, tan, or brownish; Luster: Dull/Earthy; Texture: Granular, medium-grained; Cleavage: None, breaks across grains; Specific Gravity: 2.2-2.8
- Hardness
- 6-7 Mohs
- Color
- Gray, tan, or brownish
- Luster
- Dull/Earthy
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Physical properties
Hardness: 6-7 Mohs; Color: Gray, tan, or brownish; Luster: Dull/Earthy; Texture: Granular, medium-grained; Cleavage: None, breaks across grains; Specific Gravity: 2.2-2.8
Formation & geological history
Formed through the accumulation and cementation of sand-sized mineral grains or rock fragments. Typically deposited in riverbeds, lakes, or ocean basins over millions of years (ranging from Paleozoic to recent).
Uses & applications
Used widely in construction as a building material, road base, or decorative stone. Sometimes used in glass manufacturing if the quartz content is high enough.
Geological facts
Sandstones make up roughly 20 percent of all sedimentary rocks on Earth. They are often excellent aquifers, meaning they can store large amounts of groundwater or petroleum in their pore spaces.
Field identification & locations
Identify in the field by its gritty, sandpaper-like feel. It is commonly found in desert environments, old river beds, and coastal areas. Collectors look for unique weathering patterns or fossil inclusions.
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