AVO Logo
Site Map | FAQ |
Alaska Volcano Observatory
 
You are here: Home > Samples > Snyder_1959_7

SAMPLE INFO : Snyder_1959_7
Sample ID:Snyder_1959_7
Station ID:Snyder_1959_7
Latitude:51.9531
Longitude:178.5356
Datum:NAD83
Sample Type 1:Lava
Field Lithology:Dacite
Text Description:
Low-silica dacite of Little Sitkin dacite. Color: grayish black (N 2). Texture: hypocrystalline, porphyritic with plagioclase as much as 5 mm in length. Most plagioclase megaphenocryst and microphenocrysts, 25-30 percent, group around An56 but range from An25 to An78; complex oscillatory zoning common; many feldspars contain vermicular areas of dusty brown glass. Orthopyroxene, 8-10 percent, occurs as individual euhedrons and as cores in many clinopyroxene, 6 percent, crystals. Accessory minerals: magnetite, 2 percent, and oxyhornblende, 1 percent (xenocrysts?) Fluidal glassy groundmass contains angular crystal fragments, 3 percent, and euhedral rods of pyroxene (?).

References:
Geology of Little Sitkin Island, Alaska

GEOCHEM DATA