Scoria Facts

Scoria Facts
Scoria is an igneous rock that is dark-colored with abundant bubble-like cavities called vesicles. Scoria's color can range from black or dark gray to a deep reddish brown. It has a composition similar to that of basalt, or can also have a composition similar to andesite. The small pieces of scoria look like the ash produced in a coal furnace resulting in particles of scoria being called cinders. The erupting volcanoes that release scoria are called cinder cones. The small particles that litter an area around a volcano are often called lapilli if they are between 2 and 64 millimeters in size, and the larger pieces are known as blocks.
Interesting Scoria Facts:
Magma containing abundant dissolved gas flows from a volcano or is blown out during an eruption results in the formation of scoria.
If molten rock solidifies before the gas escapes, the bubbles become small rounded or elongated cavities, which leads to scoria being produced.
The bodies that solidify in the air and become scoria produces ground cover all around the volcano vent with the heaviest deposits on the downwind side.
Scoria has an angle of repose of 30 to 40 degrees, which is very steep due to the small volcanoes produced by brief eruptions with a vertical relief less than a few thousand feet.
Sometimes newly erupted lava flows contain abundant dissolved gas, and once lava starts to solidify, the trapped gas bubbles are the vesicles, and if the upper portion has an abundant number of vesicles, it is often called scoria.
Pumice is very similar to scoria that is also a vesicular igneous rock, but there are a few differences that can distinguish them.
Scoria is usually always black or dark gray to reddish brown and pumice is white to light gray or light tan, due to their composition differences.
Pumice has a higher concentration of trapped bubbles allowing it to float, but thick walls of scoria make it heavy enough to sink.
Using a hand lens, a person can often see very tiny mineral crystals in scoria.
The production of lightweight aggregate is one of the main uses of scoria. It is crushed to the specific sizes and sold for a variety of uses.
Using concrete with scoria weighs about 100 pounds per cubic foot, but with typical sand and gravel it would weigh about 150 pounds per cubic foot.
The lighter scoria allows buildings to be constructed with less structural steel, and the air trapped in the scoria makes the concrete a better insulator resulting in lower heating and cooling costs.
Crushed scoria is used for ground cover in landscape projects, as a substrate in hydroponic gardening, and as roofing granules.
Buyers have the option of purchasing black, brown, or red material.
In addition, scoria may be used as rip-rap, drainage stone, or low-quality road metal. Small amounts of it can be used as sauna rock and as a heat sink in barbecue grills.
There are also scoria substitutes such as a lightweight aggregate that is produced by heating shale in a rotating kiln under controlled conditions.
Substitute scoria can have the same properties, appearances, and vesicles as the original, which is sold under the name "expanded clay,", or "grow rocks."

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