Question

characteristics of obsidian

Answer 1

Answer:

Characteristics of obsidian.

Answer 2

OBSIDIAN

Obsidian is a naturally occurring volcanic glass formed when lava extruded from a volcano cools rapidly with minimal crystal growth. It is an igneous rock. It is hard, brittle, and amorphous; it, therefore, fractures with sharp edges. In the past, it was used to manufacture cutting and piercing tools, and it has been used experimentally as surgical scalpel blades.

• Obsidian is mineral-like, but not a true mineral because as a glass it is not crystalline; in addition, its composition is too variable to be classified as a mineral.
• Though obsidian is usually dark in color, similar to mafic rocks such as basalt, the composition of obsidian is extremely felsic.
• Obsidian consists mainly of SiO2 (silicon dioxide), usually 70% by weight or more.
• Obsidian is produced from felsic lava, rich in lighter elements such as silicon, oxygen, aluminium, sodium, and potassium.
• Most black obsidians contain nano inclusions of magnetite, an iron oxide.
• Obsidian may contain patterns of gas bubbles remaining from the lava flow, aligned along layers created as the molten rock was flowing before being cooled.
• Newly formed obsidian has a low water content, typically less than 1% water by weight, it becomes progressively hydrated when exposed to groundwater, forming perlite.
• Tektites were once thought by many to be obsidian produced by lunar volcanic eruptions, though few scientists now adhere to this hypothesis.
• There are only four major deposit areas in the central Mediterranean: Lipari, Pantelleria, Palmarola, and Monte Arci (Sardinia).
• Obsidian is found in locations that have undergone rhyolitic eruptions. It can be found in Argentina, Armenia, Azerbaijan, Australia, etc.
• Obsidian bladelets were used in ritual circumcisions and cutting of umbilical cords of newborns. Manufacture of obsidian bladelets at Lipari had reached a high level of sophistication by the late Neolithic and was traded as far as Sicily, the southern Po river valley, and Croatia.
• Obsidian artifacts first appeared in the European continent in Central Europe in the Middle Paleolithic and had become common by the Upper Paleolithic, although there are exceptions to this. Obsidian played an important role in the transmission of Neolithic knowledge and experiences.
• The use of the old tools was founded in Japan's volcanic activity.
• Obsidian can be used to make extremely sharp knives, and obsidian blades are a type of glass knife made using naturally occurring obsidian instead of manufactured glass. Obsidian is used by some surgeons for scalpel blades, although this is not approved by the US Food and Drug Administration (FDA) for use on humans. Well-crafted obsidian blades, like any glass knife, can have a cutting edge many times sharper than high-quality steel surgical scalpels: the cutting edge of the blade is only about 3 nanometers thick.