Obsidian white dating
Like all glass and some other types of naturally occurring rocks Obsidian breaks with a characteristic "conchoidal" fracture.
Also like other glass, Obsidian is metastable at the earth's surface which means that over time the glass becomes fine-grained mineral crystals.
The resulting silica-rich magma with little remaining water becomes very viscous (thick and pasty) - obsidian magma.
This magma is so viscous that sizable mineral crystals cannot grow before the cooling of the magma "freezes" crystal development.
Obsidian is found in a number of US states, the biggest deposits being within the calderas of Newberry Volcano and Medicine Lake Volcano in the Cascade Range of western North America.
The ancient volcanic hills called Glass Buttes in Oregano hold a large variety of gem-quality obsidian, including: mahogany, red, flame, midnight lace, jet black, pumpkin, brown, rainbow, gold sheen, silver sheen, green, lizard skin, snowflake etc, so if you ever thought that Obsidian is just boring black glass, the trip to those parts might be an eye-opener.
Inclusions of small, white, radially clustered crystals of cristobalite in the black glass produce a blotchy or snowflake pattern.
This type of obsidian is commonly referred to as snowflake obsidian. Obsidian only occurs around volcanoes which have had rhyolitic eruptions.
Chemically, Obsidian closely resembles granite and rhyolite but the processes which lead to the formation of Obsidian are different to those which shape granite.
The technique measures the microscopic amount of water absorbed into freshly broken surfaces.
The longer the artifact's surface has been exposed, the thicker the hydration band will be.
The excavation of Granite Point was contracted to Washington State University and fieldwork was conducted during the summers of 19 by Washington State University faculty and field school students. The completion of dams along the Snake River flooded Granite Point Locality 1, and though the physical locality is inaccessible, the river’s waters do not prohibit its continued study.
The 1967 field season was led by Roderick Sprague, while Ph. Through the study of Granite Point’s archaeological collection, this archaeologically important site has the potential to further its contributions to understandings of prehistoric life in the Lower Snake River Region.