How to Identify Sandstone: What to Look For and Home Tests

Clastic sedimentary rocks are cemented grains of older rock: sand, silt or clay. Grain size is the first thing to judge, and layers, ripple marks or fossils confirm the sedimentary origin. The properties that identify Sandstone — cleavage or fracture: Breaks along grain boundaries, giving the broken surface a granular appearance (in contrast to quartzite). For a rock, texture and grain size matter more than any single hardness number.

• Grain test: sandstone consists of sand-sized grains (1/64 to 1/16 inch) held together by a cementing material.

• [Quartz](/lookup/rocks-and-minerals/quartz): Sandstone breaks along grain boundaries (granular fracture surface); quartzite breaks straight through the quartz grains themselves (smooth, even glassy fracture surface).

Sandstone in Colorado National Monument, the 250-million-year-old Lyons Sandstone along the eastern flank of the Front Range, and the ripple-marked Dakota Sandstone.

Photograph a fresh, unweathered surface in daylight, then a second shot of any crystal faces or broken edge. Include a coin for scale. If you did a streak test, photograph the streak next to the specimen. The app suggests the likely mineral or rock; confirm with hardness and the tests above before you label it.