Scituate Igneous Suite - rhyolite (RIDsr;0)

Scituate Igneous Suite - rhyolite

Pink to gray, fine-grained, locally porphyritic felsite (phenocrysts of quartz and Carlsbad-twinned orthoclase). Includes some hypabyssal intrusive rocks (feeder dikes and sills), and some probable lava flows. Contains accessory biotite, opaque minerals, zircon, monzonite, fluorite, sphene, apatite, and epidote. Quartz phenocrysts commonly are embayed and partly resorbed; matrix is fine-grained intergrowth of quartz and feldspar, probably formed from devitrified glass. Includes some rock mapped formerly as Spencer Hill Volcanics and Maskerchugg Granite.

State	Rhode Island
Name	Scituate Igneous Suite - rhyolite
Geologic age	Devonian
Lithologic constituents	Major Igneous > Volcanic > Felsic-volcanic > Rhyolite (Flow, Dike or sill)rhyolite - Pink to gray, fine-grained, locally porphyritic felsite (phenocrysts of quartz and Carlsbad-twinned orthoclase). Includes some hypabyssal intrusive rocks (feeder dikes and sills), and some probable lava flows. Contains accessory biotite, opaque minerals, zircon, monzonite, fluorite, sphene, apatite, and epidote. Quartz phenocrysts commonly are embayed and partly resorbed; matrix is fine-grained intergrowth of quartz and feldspar, probably formed from devitrified glass.
Comments	Part of Esmond-Dedham Subterrane (West Bay Area)
References	Hermes, O.D. (comp.), Gromet, L.P. (comp.), Murray, D.P. (comp.), Hamidzada, N.A., Skehan, J.W., and Mosher, S., 1994, Bedrock geologic map of Rhode Island: Rhode Island Map Series No. 1, Kingston, Rhode Island, scale 1:100,000.
NGMDB product	NGMDB product page for 19719
Counties	Kent - Washington

Scituate Igneous Suite - rhyolite

Hermes, O.D. (comp.), Gromet, L.P. (comp.), Murray, D.P. (comp.), Hamidzada, N.A., Skehan, J.W., and Mosher, S., 1994, Bedrock geologic map of Rhode Island: Rhode Island Map Series No. 1, Kingston, Rhode Island, scale 1:100,000.