Orthopyroxene (hypersthene) with Cordierite and Biotite
These four views show a spectacular rock from near Kazabazua, Quebec. It contains primarily cordierite and orthopyroxene with lesser amounts of biotite. The cordierite is twinned (and in XP looks a lot like plagioclase) and contains pleochoric halos around zircon inclusions. The halos appear as "burn" marks in PP light. The orthopyroxene is blocky and fractured, shows high relief (PP), and has first order interference colors (XP). It is pleochroic, with color ranging from light pink to light green. Biotite is also pleochroic and here exists as flakes in various shades of brown (PP) and has upper 2nd order interference colors (XP).
The field of view is 2.5 mm.
Orthopyroxene in a Spinel Peridotite Xenolith from Kilbourne Hole, New Mexico
These photos show mostly orthopyroxene (light clear to green, PP; gray interference color, XP). Several small grains of clinopyroxene (2nd order yellow to blue interference colors, XP) are also also present -- mostly along the left side of the photos. Note the near 90o cleavage angle in the orthopyroxene.
The field of view is 4.5 mm.
Orthopyroxene in an Olivine Websterite Xenolith from the Cima Volanic Field, California
These photos show a large grain of orthopyroxene
surrounded by clinopyroxene (some of which
is near extinction in the XP view). In the XP view, the orthopyroxene
shows only first-order interference
colors -- the clinopyroxene ranges
up to upper second order orange to pink (near the top center
of the photo). Only one well developed cleavage
is visible in this orthpyroxene grain.
Orthopyroxene in a Xenolith from the Cima Volcanic Field, California
This photos is of a large orthopyroxene grain in a xenolith from a basalt in the Cima Volcanic Field, California. The fractured orthopyroxene grain is clear (PP) and shows first-order yellow to gray interference colors (XP). The finer grained material is mostly a mix of plagioclase -- blocks and lathes (with twinning just faintly visible in the XP view) and brown volcanic glass. The field of view is 4.5 mm.