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Pig carved in snowflake obsidian, 10 centimeters (4 in) long. The markings are spherulites. Obsidian is also used for ornamental purposes and as a gemstone. [67] It presents a different appearance depending on how it is cut: in one direction it is jet black, while in another it is glistening gray.
Obsidian hydration dating (OHD) is a geochemical method of determining age in either absolute or relative terms of an artifact made of obsidian.. Obsidian is a volcanic glass that was used by prehistoric people as a raw material in the manufacture of stone tools such as projectile points, knives, or other cutting tools through knapping, or breaking off pieces in a controlled manner, such as ...
This transition is highly discontinuous. Going from the α form to the β form causes an increase in volume of 3 [10] or 4 [11] percent. The exact transition temperature depends on the crystallinity of the cristobalite sample, which itself depends on factors such as how long it has been annealed at a particular temperature.
Obsidian is a personal knowledge base and note-taking software application that operates on Markdown files. [ 3 ] [ 4 ] [ 5 ] It allows users to make internal links for notes and then to visualize the connections as a graph .
The lavas of different volcanoes, when cooled and hardened, differ much in their appearance and composition. If a rhyolite lava-stream cools quickly, it can quickly freeze into a black glassy substance called obsidian. When filled with bubbles of gas, the same lava may form the spongy appearing pumice. Allowed to cool slowly, it forms a light ...
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Obsidian projectile point.. Obsidian is a naturally formed volcanic glass that was an important part of the material culture of Pre-Columbian Mesoamerica.Obsidian was a highly integrated part of daily and ritual life, and its widespread and varied use may be a significant contributor to Mesoamerica's lack of metallurgy.
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