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Rhyolitic Tuff
Rhyolitic Tuff ( N. Carolina )
Comes in various shades of green and grey, a fine-grained to sugary texture.
Rhyolitic tuff forms from volcanic ash or dust depositions. To quote Dr.Randy Daniel, "The tuffs seen in this study, both in artifacts and at quarries, are variable in color and texture. This variability includes various shades of green to light grey and both fine and somewhat coarse-grained stone." (Hardaway Revisited,p44) "Felsic tuff" corresponds to plagioclase porphyritic rhyolite. This type of rhyolite is characterized by rhe presence of phenocrysts : (1) plagioclase porphyritic,(2)quartz porphyritic, and (3)plagioclase-quartz porphyritic. These phenocrysts are quartz and/or feldspar. This type is often called speckled rhyolite. The colors are quite variable.
Comes in various shades of green and grey, a fine-grained to sugary texture.
Rhyolitic tuff forms from volcanic ash or dust depositions. To quote Dr.Randy Daniel, "The tuffs seen in this study, both in artifacts and at quarries, are variable in color and texture. This variability includes various shades of green to light grey and both fine and somewhat coarse-grained stone." (Hardaway Revisited,p44) "Felsic tuff" corresponds to plagioclase porphyritic rhyolite. This type of rhyolite is characterized by rhe presence of phenocrysts : (1) plagioclase porphyritic,(2)quartz porphyritic, and (3)plagioclase-quartz porphyritic. These phenocrysts are quartz and/or feldspar. This type is often called speckled rhyolite. The colors are quite variable.