A Geoscience Digital Image Library

TitleThin section of monzonite
DescriptionThis is a cross polarized thin section of monzonite. Hetrogranular texture with a few large cloudy orthoclase crystals with poikilitic plagioclase and mafic inclusions. Some potash feldspar has rims of granophyre that also forms interstitial patches. Dominant plagioclase ranges in size considerably and shows gradational zoning. Augite is partly or wholly uralitized to very weakly pleochroic green hornblende. Biotite is in part chloritized. Coarse granular magntite is common; apatite and zircon are rare.
ChronostratigraphyTertiary (Miocene)
LocationUSA ▹ Colorado ▹ San Juan. Near Silverton.
PhotographerDarla Sondrol. 2002-04-08.
CollectionWard’s Collection of Classic North American Rocks #22.
Key wordsmonzonite, Colorado
Tech details935 KB. Thin section. Nikon FDX-35.
GeoDIL number2624