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Igneous rocks Reference Libraries

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Mount Nyiragongo
2014-08-28 11:22:30

Mount Nyiragongo is an active stratovolcano that is located in the Democratic Republic of the Congo. This volcano is part of the Virunga Mountains and is located in Virunga National Park. It reaches an elevation of 11,385 feet and has a crater that reaches 1.2 miles in width. This crater typically holds a lava lake that has varied between 2,000 and 10,660 feet in depth. It is not known how long...

Chaitn
2014-08-28 10:38:21

Chaitén is a volcanic caldera that is located in southern Chile that reaches an elevation of 3,681 feet. It is thought that this volcano once held a rhyolite obsidian lava dome that reached 3,156 in height, but this was destroyed after its most recent eruption in 2008. In the past, this volcano has released grey obsidian, which was used by pre-Columbian cultures to make many objects, some of...

Huallai
2014-04-10 12:06:55

Hualālai is a dormant shield volcano that is located on the island of Hawaii and is one of five volcanoes that form the island. It reaches an elevation of 8,271 feet and is thought to have emerged from the sea about 300,000 years ago, making it the third youngest volcano on the island. Its shape is rough compared to younger volcanoes and it holds three rift zones that are covered with over one...

Kohala
2014-04-10 10:03:58

Kohala is an extinct shield volcano that is located on the island of Hawaii and reaches an elevation of 5,480 feet. It is one of five volcanoes that comprise the island of Hawaii and is thought to be about one million years old, although it only emerged from the sea about 500,000 years ago. Because its last eruption is thought to have occurred about 120,000 years ago, based on studies conducted...

Askja
2014-04-09 16:13:20

Askja is an active stratovolcano that is located in the isolated central highlands in Iceland. It reaches an elevation of 4,974 feet and its name literally means caldera, or box, in the Icelandic language. The area can only be reached during a period of a few months and because it located in the rain shadow of the Vatnajökull glacier to the northeast, it only receives 17.7 inches of rain per...

Eldfell
2014-04-08 12:54:37

Eldfell is an active stratovolcano that is located in Iceland on the island of Heimaey, in the Vestmannaeyjar archipelago. It reaches an elevation of 656 feet and was created during a volcanic eruption on the east side of the island in 1973. Its name means Mountain of Fire in the Icelandic language. Iceland is an area with a high frequency of volcanic activity because it is located on top of...

Klauea
2014-04-08 12:33:13

Kīlauea is an active shield volcano that is located on the island of Hawaii and is located within Hawaii Volcanoes National Park. This volcano, which reaches an elevation of 4,091 feet, is one of five volcanoes that form the island and it is the most active. It is thought to be between 300,000 and 600,000 years old and is the second youngest of all the Hawaii volcanoes. It was formed when the...

Mauna Loa
2014-04-08 12:02:09

Mauna Loa is an active shield volcano that is located on the island of Hawaii and is one of five volcanoes that form the island. It reaches an elevation of 13,679 feet, slightly shorter than Mauna Kea, but it is still considered one of the volcanoes on Earth due to its length and depth. Its name means Long Mountain in the Hawaiian language. This volcano is thought to have emerged from the ocean...

Biotite
2005-05-26 12:03:39

Biotite is a common phyllosilicate mineral that contains potassium, magnesium, iron and aluminium. It is sometimes called "iron mica" and is found in granitic rocks, gneisses, and schists. Like other mica minerals, biotite has a highly perfect basal cleavage, its flexible sheets easily flaking off. It has a hardness of 2.5 - 3, a specific gravity of 2.7 - 3.1, is colored greenish to brown or...

Diorite
2005-05-26 11:01:52

Diorite is a grey to dark grey intermediate intrusive igneous rock composed principally of plagioclase feldspar (typically andesine), hornblende, and/or pyroxene. Varieties deficient in hornblende and other dark minerals are called leucodiorite. It is often described as "salt and pepper" when composed largely of light-colored minerals randomly interspersed with dark minerals. When olivine and...

Word of the Day
donative
  • A gift; a largess; a gratuity; a present; a dole.
The word 'donative' comes from a Latin word meaning 'to give'.
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