GRD000GS0
I-17
Obsidian
Mesozoic › Cretaceous
65.5
-
145.5
1
Ritter 154 › Cabinet 15 › Drawer M
altered
Spherulitic Obsidian
-
-
California
Alpine
Latitude: 32.8°
Longitude: -116.8°
N/A
Slight alteration in plagioclase. Note the radiation halos around the zircons inclusions in the biotite.
2.5
plane
Polysynthetic twinning in plagiocalse. Brown biotite.
2.5
crossed
-
scan
crossed
GRD000GT0: 50% Plagioclase (albite and polysynthetic twinning), 30% quartz, 15% biotite, <1% opaque oxides, trace zircon with radiation halos in biotite, sphene? Some myrmekitic texture. Slightly altered. (C. Eichler)
N/A
McDougall_JGSAustralia_1964
McDougall, I. 1964. Differentiation of the great lake dolerite sheet, Tasmania: Journal of the Geological Society of Australia, vol. 11, Iss. 1, pgs 107-132.