metamorphic
Gray Slate Pebble
Slate (metamorphosed mudstone/shale)
Mohs hardness of 2.5-4, dull to earthy luster, fine-grained texture with subtle slaty cleavage lines, dark gray color, microcrystalline structure composed mainly of quartz, chlorite, and micas.
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Physical properties
Mohs hardness of 2.5-4, dull to earthy luster, fine-grained texture with subtle slaty cleavage lines, dark gray color, microcrystalline structure composed mainly of quartz, chlorite, and micas.
Formation & geological history
Formed through low-grade regional metamorphism of mudstone or shale under low heat and pressure conditions. This small pebble has been smoothed and rounded by water action in a river or coastal beach environment.
Uses & applications
Larger slate deposits are used in roofing, flooring, and pool tables; small water-worn slate pebbles are mostly collected for landscaping, craft projects, or casual rock collections.
Geological facts
Slate can split into thin, flat sheets due to slaty cleavage caused by parallel alignment of microscopic platy minerals. River-tumbled slate pebbles often lose their sharp cleavage edges and become smooth, flat stones.
Field identification & locations
Identified by its fine grain, dull gray appearance, flat/tabular rounded pebble shape, and soft texture compared to quartz-rich pebbles. Commonly found along riverbeds, lakeshores, and ocean beaches near metamorphic rock formations.
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