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Igneous Rock
Igneous rock is formed from cooled magma or lava. The magma turns solid as it cools, and eventually becomes rock. It is sometimes crystallized.
1,149 Questions
Randomly arranged interlocking crystals and no fossils :)
What is a type of rock formed by cooled magma?
Igneous rock is formed from the solidification of magma as it cools.
Why are basalt and granite the most common rocks of the crust?
Because they are the product of eutectic melting and density separation of the melts.
What two geological processes are involved in changing igneous rock to sedimentary rock?
The geological processes, that are involved in changing igneous rock to sedimentary rock are; weathering, erosion, deposition and compaction.
What is an igneous rock that is gray and floats in water?
Pumice is a grey volcanic rock so full of gas bubbles that it is able to float on water.
How are igneous rocks named based on composition and texture?
Texture:
Aphanitic -- small crystals, invisible without magnification
Porphyritic -- visible crystals amid a fine-grained groundmass
Phaneritic -- large visible crystals
Composition:
Felsic -- more than 65% silica
Intermediate -- between 55-65% silica
Mafic -- between 45-55% silica
Ultramafic -- less than 45% silica
Why is basalt classified as an igneous rock?
Basalt is considered igneous because it forms when mafic lava cools at Earth's surface.
What do igneous rocks tend to be?
Igneous rock is formed by the cooling and solidification of magma or lava
What Evidence Would You Look For If Attempting To Classify A Piece of igneous Rock as Extrusive?
Extrusive igneous rocks have very small crystal grains.
What is a lens-shaped intrusive igneous mass that forms close to Earths surface?
I believe it's laccolith - NovaNet
Igneous rocks can look very different depending on?
Igneous rocks look different depending on how fast the magma cools.
What igneous rock contains mostly plagioclase feldspar and about 30 percent dark silicates?
A Diorite.
What is the fracture of diorite?
Diorite is an igneous rock, and does not have a cleavage , but a break between two sections of diorite could be best described as 'uneven'
How does one make a cutting tool with obsidian?
Making a cutting tool using obsidian rock is quite easy. The cavemen used to smack pieces of obsidian with other rocks until the obsidian was thin and sharp as a knife.
What are the five varieties of quartz crystals?
There are many varieties of quartz crystals that can be considered classifications beyond just five. Some of the names for the varieties are Macrocrystalline, Microcrystalline and Cryptocrystalline.
How come lava doesn't burn Igneous rocks?
Ignoues rock is not flammable, therefore it does not burn. In order to melt the igneous rock, the lava must transfer an enormous amount of heat to it. However, lava will quickly lose heat to its surroundings and will generally cool before it can do this.
How can you tell that gabbro crystalized deeper underground than basalt did?
Gabbro has larger crystals, meaning it had much more time to solidify from magma underground. Larger crystals in igneous rock are an indication of longer cooling times, which result in larger crystal growth.
How many years would it take radioactive decay in a kilogram of granite to produce this many joules?
The time it takes for radioactive decay in a kilogram of granite to produce a specific amount of energy in joules depends on the specific radioactive isotopes present in the granite, as different isotopes have different decay rates. Granite typically contains trace amounts of uranium, thorium, and potassium isotopes, which decay at different rates and produce different amounts of energy. Detailed calculations would be needed to determine the exact time based on the specific isotopic composition and decay rates in the granite sample.
