A natural cleft or riven face is simply achieved by splitting blocks of stone.
 Oyster |
 Desert Sunset
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 Oyster
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Schist is a metamorphic rock, usually formed when the rock shale, is
put under great pressure. Top and bottom layers are usually a silvery,
to green, to brown, to black. Layers are usually thin, and may be
somewhat wavy. Grain size varies from medium to coarse.
