Milford granite

Light-gray to pale orange-pink biotite granite; biotite tends to be in clots or short streaks, quartz granular; locally gneissic. Intrudes Zb. Occupies an area of about 100 sq km. Central mass near Milford is elliptical and is divided into and mapped as a light-colored phase and a dark-colored phase; dark-colored phase defines an irregular border for largest of light-colored plutons. Intrudes Blackstone Group rocks and Ponaganset Gneiss, but was deformed with them at some later unknown time. Isotopic age of 630 +/-15 Ma was determined using U-Pb methods on zircon by Zartman and Naylor (1984). Characterized by salmon-pink color, bluish quartz on weathered surfaces, and lineations defined by lenticular mosaics of quartz and oriented patches of biotite; texture contrast strongly with that of Dedham Granite (Wones and Goldsmith, 1991).
State Massachusetts
Name Milford granite
Geologic age Proterozoic Z
Lithologic constituents
Major
Igneous > Plutonic > Granitic > GraniteLight-gray to pale orange-pink biotite granite; biotite tends to be in clots or short streaks, quartz granular; locally gneissic.
Comments Part of Milford-Dedham Zone (Tertiary and Older Rocks). Secondary unit description per MA007.
References
NGMDB product
Counties Middlesex - Worcester