Little Ring Mountain at the northern end of the field contains at least 70 % brown volcanic glass with isolated phenocrysts of plagioclase.
32.
Another technique used by archaeologists is to inspect the depth of penetration of water vapor into chipped obsidian ( volcanic glass ) artifacts.
33.
For instance, water causes magma to cool and solidify much more quickly than in a terrestrial eruption, often turning it into a volcanic glass.
34.
When heated to their melting point, terrestrial volcanic glasses will turn into a foamy glass because of their content of water and other volatiles.
35.
Although tektites are superficially similar to some terrestrial volcanic glasses ( obsidians ), they have unusual distinctive physical characteristics that distinguish them from such glasses.
36.
The fad is first used to put a thinned coat of shellac on, then thicker coats with small amounts of superfine pumice, a crushed volcanic glass.
37.
Named after the volcanic glass crystals found in the soil, Diamond Mountain rises above the valley west of Highway 29 between St . Helena and Calistoga.
38.
In stratigraphy and tephrochronology, completely devitrified ( weathered volcanic glass ) ash-fall beds are commonly referred to as K-bentonites when the dominant clay species is illite.
39.
Crossed polarized light image of melilite in Moiliili lava flow, Moiliili Quarry, Honolulu, O ahu, Hawai i surrounded by matrix of granular nepheline and volcanic glass.
40.
The often rarely preserved flow top breccia and pillow margin zones in some komatiite flows are essentially volcanic glass, quenched in contact with overlying water or air.
