Usually dark, the color varies on the presence of different materials. Iron and magnesium typically give the obsidian a dark green to brown to black color. A few samples are nearly colorless. In some stones, small crystals produce a snowflake pattern ("snowflake obsidian"). It may contain patterns of gas which produce effects such as a golden sheen ("sheen obsidian") or a rainbow sheen ("rainbow obsidian").
Obsidian was valued in Stone Age cultures because, like flint, it could be chipped to produce hand axes, sharp blades or arrowheads.
Pre-Columbian Mesoamericans' used obsidian often. It was worked for tools and decorative objects. It was also polished to create early mirrors. Mesoamericans also made a type of sword with obsidian blades mounted in a wooden body. Called a macuahuitl, the weapon could cause terrible injuries, because it combined the sharp cutting edge of an obsidian blade with the ragged cut of a serrated edge.
Native American people traded obsidian throughout North America. Each volcano and in some cases each volcanic eruption produces a distinguishable type of obsidian. So archaeologists can trace the origins of a particular artifact. Obsidian can be identified in Greece as coming from different islands in the Aegean Sea. Obsidian cores (unworked lumps) and blades were traded great distances inland from the coast.
Modern archaeologists have developed a dating system to calculate the age of obsidian artifacts depending from the content of water in the object.
Obsidian can be found where high silicate eruptions have happened. There are solid obsidian flows in the calderas of Newberry Volcano and Medicine Lake Volcano in the Cascade Range of western North America, and at Inyo Craters east of the Sierra Nevada, California. Yellowstone National Park has a mountainside containing obsidian between Mammoth Hot Springs and the Norris Geyser Basin. Deposits can be found in many other western US states including Arizona, Colorado, Texas, Utah, Oregon and Idaho. Obsidian can also be found in Armenia, Turkey, Italy, Mexico, Iceland, Greece and Scotland.
Obsidian is used in heart surgery, as well-crafted obsidian blades have a cutting edge many times sharper than high-quality steel surgical scalpels, with the edge of the blade being only about 3 nm wide. Even the sharpest metal knife has a jagged, irregular blade when viewed under a strong enough microscope. When examined under an electron microscope an obsidian blade is still smooth and even. One study found that obsidian produced narrower scars, fewer inflammatory cells, and less granulation tissue in a group of rats.
Obsidian is also used for ornamental purposes and as a gemstone. It possesses the property of presenting a different appearance according to the manner in which it is cut. When cut in one direction it is a beautiful jet black; when cut across another direction it is glistening gray.
Obsidian (disambiguation)
Obsidian can refer to:
Isle of Arran
Arran or the Isle of Arran is the largest island in the Firth of Clyde, Scotland.
With an area of it is the seventh largest Scottish island. Just over 5,000 people live there.
Arran shares with the Hebrides cultural and physical similarities. Arran is mountainous and has been described as a "geologist's paradise".
People have lived there since the early Neolithic period, from which time on there are numerous prehistoric remains.
From the 6th century on peoples from Ireland colonised the island and it became a centre of religious activity. During the troubled Viking Age, Arran became the property of the Norwegian crown before becoming formally absorbed by the Kingdom of Scotland in the thirteenth century.
The 19th century "clearances" led to significant reductions in population and the end of the Gaelic language and way of life.
The economy and population have recovered in recent years, the main industry being tourism. There is diversity of wildlife, including three species of tree endemic to the area. There are regular field trips in the summer by geology and biology students.
The island is sometimes referred to as "Scotland in miniature", as it is divided into "Highland" and "Lowland" areas by the Highland Boundary Fault which runs northeast to southwest across Scotland.
The island is a popular destination for geologists, who come to see intrusive igneous landforms such as sills and dykes as well as sedimentary and metasedimentary rocks ranging in age from Precambrian to Mesozoic.
Most of the interior of the northern half of the island is taken up by a large granite batholith that was created by substantial volcanic activity around 60 million years ago in the Tertiary period. There is an older outer ring of coarse granites and an inner core of finer grained material.
Sedimentary rocks dominate the southern half of the island, especially Old and New Red Sandstone. Sand dunes are preserved in Permian sandstones near Brodick, there are localised outcrops of Triassic rocks, and even some Cretaceous chalk.
Visiting in 1787, the geologist James Hutton found his first example of an unconformity to the north of Newton Point near Lochranza. It showed evidence for his Plutonist theories of uniformitarianism, and about the age of the Earth. This spot is one of the most famous places in the study of geology.
The Pleistocene glaciations almost entirely covered Scotland in ice. After the last retreat of the ice at the close of the Pleistocene epoch sea levels were up to lower than at present and it is likely that circa 14,000 years ago the island was connected to mainland Scotland.
Sea level changes and the isostatic rise of land makes charting coastlines a complex task, but the island is clearly ringed by post glacial raised beaches.
What this means is that the huge weight of ice pressed down the Earth's crust here, and so the beaches were much higher up than now. Gradually, long after the ice melted, the island came back up.
King's Cave on the south west coast is an example of such a raised beach. This cave, which is over long and up to high, lies well above the present day sea level.
There are tall sea cliffs to the north east including large rock slides under the heights of Torr Reamhar and at Scriden ("An Scriodan") at the far north end of the island. The Scriden rocks fell "some two hundred years ago, with a concussion that shook the earth and was heard in Bute and Argyllshire".
Kurud
Kurud is a town found in the center of the state of Chhattisgarh in India.
Germanic paganism
Germanic paganism was a religion. It was a form of paganism. It was practiced in Central and Northern Europe before Christianity came there. The best documented form is called Norse paganism today. The religion was polytheistic, there were many gods. The main ones seem to have been Odin and Thor. Beforehand, the most important one may have been Tyr.
The Germanic gods have affected elements of every day western life in most countries that speak Germanic languages. An example is some of the names of the days of the week. The days were named after Roman gods in Latin (named after "Sun, Moon, Mars, Mercury, Jupiter, Venus, Saturn"). The names for Tuesday through Friday were replaced with Germanic versions of the Roman gods. In English and Dutch, Saturn was not replaced. Saturday is named after the Sabbath in German, and is called "washing day" in Scandinavia.
Also, many place names such as Woodway House, Wansdyke, Thundersley and Frigedene are named after the old deities of the English people.
Miguel Ángel Asturias
Miguel Ángel Asturias Rosales (October 19, 1899 - June 9, 1974) was a writer and diplomat from Guatemala. He was awarded the Nobel Prize in Literature in 1967 for his "Banana Trilogy". He also wrote "El Hombre que lo tenía todo todo todo".
He was very important for literature in his country.
Hindustan
The term Hindustan may relate to various aspects of three geographical areas:
Hindustan can also refer to the following:
Plymouth Colony