
sedimentary
Iron-rich sandstone or ferruginous conglomeratic sandstone
Ferruginous sandstone, primarily quartz (SiO₂) cemented or stained by iron oxides/hydroxides
AI-generated identification · may be incorrectBrown to rusty orange, granular and porous, with visible sand- to pebble-sized grains; dull to earthy luster and no obvious cleavage. Quartz grains have Mohs hardness 7, while the overall rock is typically moderately hard (about 5–7) and specific gravity commonly 2.3–2.7.
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Physical properties
Brown to rusty orange, granular and porous, with visible sand- to pebble-sized grains; dull to earthy luster and no obvious cleavage. Quartz grains have Mohs hardness 7, while the overall rock is typically moderately hard (about 5–7) and specific gravity commonly 2.3–2.7.
Formation & geological history
Formed when quartz-rich sand, locally mixed with small pebbles, was deposited and lithified; iron-bearing groundwater produced the orange-brown cement or staining. Age cannot be determined from the image and may range from Precambrian to recent sedimentary deposits.
Uses & applications
Used locally as building or landscaping stone and occasionally as a decorative specimen; generally has little gemstone value.
Geological facts
The rusty coloration reflects oxidation of iron minerals such as hematite and goethite. Its irregular cavities and rounded grains may indicate weathering, porous cementation, or conglomeratic texture.
Field identification & locations
Identify it by gritty texture, visible quartz grains, rusty coloration, and lack of crystalline cleavage; a streak test may leave a pale brown to reddish mark. Common in arid, coastal, river, and iron-rich sedimentary environments.
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