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Neither. It has no visible grain.
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Does obsidian a glassy rock have a large grain size or a small grain size?
Actually, obsidian doesn't have grains at all. Technically obsidian is a glass, which means it has no internal structure. When geologists refer the the grain size of a rock, they mean how big the crystals that make it up are. Since obsidian has no crystals, it therefore has no grain size.
Did obsidian cool quickly or slowly?
Obsidian cooled very quickly. It's a vulcanic glass, meaning that the crystals are so small, they had virtually no time to form an orderly crystalline texture, and are basically placed randomly. Smaller grain size is associated with faster cooling.
How does texture affect grain size in rock?
It doesn't. The grain size effects the texture. If a rock has a small grain size, it will have a smooth texture. If the grain size is large, such as pebbles, the texture will be rough. For example, siltstone is one of the smoothest rocks because it contains silt particles, which are .0004cm to .006cm. Conglomerate though contains various particles including cobbles and boulders, which are from 10cm to 100cm.
What is the grain size of quartzite?
it is small depending on the colors
How much inches high wide and deep is obsidian?
Obsidian is a naturally occurring glass formed as an extrusive igneous rock. It is produced when acidic lava,extruded from a volcano cools very rapidly, freezing without sufficient time for crystal growth.Obsidian is commonly found within the margins of rhyolitic lava flows known as obsidian flows, where cooling of the lava is rapid.Because of the lack of crystal structure, obsidian blade edges can reach almost molecular thinness, leading to its ancient use as stone age knives and arrowheads, and its modern use as surgical scalpel blades.Obsidian can be found as lumps of rock of any size up to and including an entire mountainside.Obsidian has several varieties. Obsidian can contain small bubbles of air that are aligned along layers created as the molten rock was flowing just before being cooled. These bubbles can produce interesting effects such as a golden sheen, known as Sheen Obsidian or a rainbow sheen called Rainbow Obsidian. Inclusions of small, white, radially clustered crystals of cristobalite in the black glass produce a blotchy or snowflake pattern producing Snowflake Obsidian. Small nuggets of obsidian that have been naturally rounded and smoothed by wind and water are called Apache Tears.Often confused with smoky quartz, obsidian has similar properties to quartz because of a similar chemistry. However, many properties dependant on a crystal structure are altered or absent in obsidian because it lacks any crystal structure of its own. The piezoelectric and optical properties in quartz are thus absent in obsidian. Smoky quartz usually has a splotchy or zoned distribution to its color while Obsidian's color is more uniformly distributed.
Does obsidian a glassy rock have a large grain size or a small grain size?
Actually, obsidian doesn't have grains at all. Technically obsidian is a glass, which means it has no internal structure. When geologists refer the the grain size of a rock, they mean how big the crystals that make it up are. Since obsidian has no crystals, it therefore has no grain size.
What is obsidian's grain size?
there is no visible grain size
What is the grain size of dacite?
Small to medium grain size.
Did obsidian cool quickly or slowly?
Obsidian cooled very quickly. It's a vulcanic glass, meaning that the crystals are so small, they had virtually no time to form an orderly crystalline texture, and are basically placed randomly. Smaller grain size is associated with faster cooling.
Name the heavenly bodies which you see as shooting stars.?
Meteors. Usually they are very small objects, about the size of a grain of sand.Meteors. Usually they are very small objects, about the size of a grain of sand.Meteors. Usually they are very small objects, about the size of a grain of sand.Meteors. Usually they are very small objects, about the size of a grain of sand.
What is Grain size of metamorphic rock?
It varies some metamorphic rocks are fine grained (eg slate) and others have very large crystals (eg an augen gneiss).
Explain pegmatite is coarse grained with large crystals basalt is fine grained with small crystals and obsidian has no crystals?
Crystal size in these rock types is determined by their rate of cooling. Pegmatites have large crystals due to very slow cooling. Obsidian has microscopic crystals due to almost instantaneous cooling.
What is a small grain size rock?
clay
Grain size for bituminous coal?
small
How does texture affect grain size in rock?
It doesn't. The grain size effects the texture. If a rock has a small grain size, it will have a smooth texture. If the grain size is large, such as pebbles, the texture will be rough. For example, siltstone is one of the smoothest rocks because it contains silt particles, which are .0004cm to .006cm. Conglomerate though contains various particles including cobbles and boulders, which are from 10cm to 100cm.
Is obsidian found anywhere in upstate new york?
My 8 year old found a large piece of obsidian in dansville ny this weekend. We are amazed by its size and beauty
What is the grain size of quartzite?
it is small depending on the colors
