Search results
Results from the WOW.Com Content Network
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 ...
Obsidian scalpels older than 2100 BC have been found in a Bronze Age settlement in Turkey. [48] In the eastern Mediterranean area the material was used to make tools, mirrors and decorative objects. [49] The use of obsidian tools was present in Japan near areas of volcanic activity. [50] [51] Obsidian was mined during the Jōmon period.
Because the Glass Buttes complex has abundant, high-quality obsidian, the Bureau of Land Management has reserved 36 square miles (93 km 2) as a free-use area where the public can gather obsidian for private use. No permits are required; however, individuals can only remove 250 pounds (110 kg) of obsidian per year.
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.
The terms lava stone and lava rock are more used by marketers than geologists, who would likely say "volcanic rock" (because lava is a molten liquid and rock is solid). "Lava stone" may describe anything from a friable silicic pumice to solid mafic flow basalt, and is sometimes used to describe rocks that were never lava , but look as if they ...
QAPF diagram with basalt/andesite field highlighted in yellow. Andesite is distinguished from basalt by SiO 2 > 52%. Andesite is field O2 in the TAS classification.. Andesite is an aphanitic (fine-grained) to porphyritic (coarse-grained) igneous rock that is intermediate in its content of silica and low in alkali metals.
Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!
Peperino has been used in Rome and Naples as a building stone, is a trachyte tuff. Pozzolana also is a decomposed tuff, but of basic character, originally obtained near Naples and used as a cement , but this name is now applied to a number of substances not always of identical character.