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They aren't found in igneous matrix only. Agates are formed in gas cavities in volcanic rock, as well as in cracks and holes in metamorphic and sedimentary rocks. Solutions high in silica content filled these cavities to form silica gel which hardened to the agate we know.
Generally, the formation temperatures are now thought to have been between 40 and 270degrees centigrade, perhaps more to the lower end of this range. Theory of agate formation has evolved with better microscopes and continued study over the years. Books by Roger K. Pabian are recommended.
At any rate, there were no human witnesses to the formation of agates, and we are still learning about these fascinating gems.
What else can I help you with?
Are igneous rocks made up of igneous rocks?
Sedimentary rock can be made up partially of igneous clasts, but igneous rock is igneous rock.
When magma is cooled it becomes what?
Cooling and solidifying magma turns into igneous rock.
What do you call rocks that have been formed from the hot molten material within the earth's crust that has cooled and hardened?
Igneous rocks are formed by the solidification of molten materials.
Is Stonehenge a sedimentary igneous or metamorphic?
igneous
What kind of rock is formed after a volcano erupts?
Extrusive igneous rock such as basalt, rhyolite, pumice, and obsidian.
Are agates metamorphic igneous or sedimentary?
Agates are none of the above rock types, but a form of the mineral quartz, normally formed as a gas vesicle filler in igneous rocks, the microcrystalline quartz gradually filling the cavity with successive layers.
When were agates found?
Agates have been found and used for ornamental purposes for thousands of years. They are typically formed in igneous rock formations and have been collected by humans for their beauty and believed metaphysical properties.
Where do agates form?
Agates form in igneous rocks such as lava flows and in sedimentary rocks such as limestone and shale. They are typically found in volcanic and metamorphic environments, where silica-rich fluids are able to penetrate cavities in the rock, forming the characteristic banded patterns that agates are known for.
Are Landscape agates or moss agates are precious?
semi precious
Do agates react different in water?
This site will explain:* http://cash-and-treasures-wiki.travelchannel.com/page/Origin+of+Agates?t=anon
How does one find agates on a beach?
As with most things, agate hunting is an acquired skill and simply reading the answer will not make you an expert! The following field guide will give you some tips on how and where to find agates on a pebble beach. Bret Fogelberg http://www.123agates.com/subpages/fieldguide.pdf
Where can you find agates?
Agates can be found in various places around the world, including river beds, volcanic rocks, and areas with geothermal activity. Some popular locations for finding agates include the beaches of Lake Superior in the United States, the coasts of Brazil and Uruguay, and the state of Gujarat in India. Additionally, agates can also be found in certain regions of Australia, Mexico, and Germany, among others.
What are the different kinds of agates?
Moss Agate and Turritella Agate
Where can you sell raw unpolished agates?
eBay is one place.
How much money per pound is agates worth?
The value of agates can vary greatly depending on factors like size, quality, and color. In general, the price of agates can range from a few dollars per pound for common varieties to hundreds of dollars per pound for rarer and more valuable specimens.
Where are Tennessee Agates found?
Tennessee Agates are primarily found in the areas surrounding the Cumberland Plateau in Tennessee, United States. Some specific locations include the counties of Smith, Warren, and White.
How do agates turn into skip-an-atom agates?
Skip-an-atom agates form when the initial agate formation process is disrupted or halted, leading to irregular banding patterns and gaps in the crystal structure. This can be caused by changes in the mineral composition, temperature, or pressure during formation. The skipping of atoms results in unique and visually striking patterns in the agate.
