Gyrolite

Field of view: 5 mm. A group of gyrolite. The micaceous silver-white crystals are gyrolite exhibiting cleavage along the basal plane. The surrounding black host is andesite, and the vesicule is filled with gyrolite. The two dark brown grains at the left of gyrolite are phenocrysts of augite.

Recovered from a vesicule of an andesitic pillow lava of Hosoonotaki Volcanics Member.

Gyrolite from this location was described in 1974.