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SAMPLE INFO : 268
Sample ID:268
Station ID:268
Latitude:55.19
Longitude:-160.5
Datum:NAD83
Date Sampled:1895-01-01
Sample Type 1:Lava
Field Lithology:Andesite
Text Description:
An andesite from Delarof Harbor, near which the Apollo mine is situated, forms in some respects a transition between the lava of St. Augustine and the more usual type of pyroxene-andesites. It is a greenish-black, somewhat vesicular porphyry, in which the microscope shows phenocrysts of augite, a rhombic pyroxene, which in this case seems to be enstatite rather than bronzite, and labradorite. The groundmass consists of "felted" feldspar microlites, a little augite, a little magnetite, and a considerable amount of glass. The feldspathic microlites are mainly alkaline labradorite, while the phenocrystic crystals are more calcareous, approaching Ab3 An4; but some of the microlites have angles of extinction appropriate to oligoclase. The slide shows decomposition products, especially chlorite, but not in important quantities.

References:
Reconnaissance of the gold fields of southern Alaska with some notes on general geology

GEOCHEM DATA