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Home > Explore! > Surficial Geology > Field Localities > Big Rock, Waltham > Figure 4




Figure 4. Big Rock is primarily composed of granite, a type of rock containing the minerals quartz (medium gray), two varieties of feldspar (white to light gray), and biotite mica (black). The pinkish color on the rock is due to weathering of the granite. (Penny for scale)


Last updated on November 20, 2012