The phenocrysts in this porphyritic granite are inclusion-rich, clay-altered, subhedral plagioclase blocks that do not appear to be in equilibrium with the surrounding groundmass. The groundmass is a mottled smattering of quartzofeldspathic minerals that have no discernable crystal habit. Amidst the background blur of first-order whites and grays are petrographically messy clusters of chlorite, hornblende, and iddingsite, with growth of chlorite and iddingsite at the expense of hornblende. Large, prismatic and hexagonal apatite crystals are readily apparent in this thin section. A few prismatic crystals of monazite, zircon, or xenotime are present (though difficult to definitively identify).
The author has given permission for this work to be deposited in the Digital Archive of Colorado College.
The author has given permission for this work to be deposited in the Digital Archive of Colorado College.
