Scoria

	Email		Print
	Bookmark		Link

Scoria

Scoria is a textural term for macrovesicular

Vesicular texture

Vesicular texture is a volcanic Rock texture characterised by, or containing, many vesicles. The texture is often found in extrusive aphanite, or glassy, igneous rock....
volcanic rock

Volcanic rock

Volcanic rock is an igneous rock of Volcano origin.Texture Volcanic rocks are usually fine-grained or aphanitic to glassy in texture....
. It is commonly, but not exclusively, basalt

Basalt

Basalt is a common extrusive volcanic rock. It is usually gray to black and fine-grained due to rapid cooling of lava at the surface of a planet....
ic or andesitic

Andesite

Andesite is an igneous rock, volcanic rock, of Igneous rock#Chemical classification, with aphanitic to porphyritic texture. The mineral assemblage is typically dominated by plagioclase plus pyroxene and/or hornblende....
in composition. Scoria is light as a result of numerous macroscopic ellipsoidal vesicles, but most scoria has a specific gravity

Specific gravity

Specific gravity is defined as the ratio of the density of a given solid or liquid substance to the density of water at a specific temperature and pressure, typically at 4?C and , making it a dimensionless quantity ....
greater than 1, and sinks in water. The vesicularity results from the exsolution of magmatic volatiles prior to chilling. Scoria differs from pumice

Pumice

Discussion

Ask a question about 'Scoria'

Start a new discussion about 'Scoria'

Answer questions from other users

Full Discussion Forum

Encyclopedia

Scoria is a textural term for macrovesicular

Vesicular texture

Vesicular texture is a volcanic Rock texture characterised by, or containing, many vesicles. The texture is often found in extrusive aphanite, or glassy, igneous rock....
volcanic rock

Volcanic rock

Volcanic rock is an igneous rock of Volcano origin.Texture Volcanic rocks are usually fine-grained or aphanitic to glassy in texture....
. It is commonly, but not exclusively, basalt

Basalt

Basalt is a common extrusive volcanic rock. It is usually gray to black and fine-grained due to rapid cooling of lava at the surface of a planet....
ic or andesitic

Andesite

Specific gravity

Pumice

File:Pumice stone444.jpgFile:Pumice stone detail444.jpgPumice is a textural term for a volcanic rock that is a solidified frothy lava typically created when super-heated, highly pressurized rock is violently ejected from a volcano....
in having larger vesicles and thicker vesicle walls, and hence is typically darker in colour (generally dark brown, black or red) and denser. The textural difference is probably the result of lower magma viscosity, allowing rapid volatile diffusion, bubble growth, coalescence, and bursting. Scoria may form as part of a lava or as fragmental ejecta (lapilli, blocks and bombs) for example at Strombolian eruptions that form steep-sided scoria cones. Most scoria is composed of glassy fragments, and may contain phenocrysts. An old name for scoria is cinder.

The word comes from the Greek

Greek language

Greek is an Indo-European languages native to the southern Balkan peninsula, the language of the Greek people. It forms an independent branch within Indo-European....
s????a, skoria, rust.

How it is formed

As rising magma encounters lower pressures, dissolved gases are able to exsolve and form vesicles. Some of the vesicles are trapped when the magma chills and solidifies. Vesicles are usually small, spheroidal and do not impinge upon one another, instead they open into one another with little distortion. Volcanic cone

Volcanic cone

Volcanic cones are among the simplest volcano formations in the world. They are built by fragments thrown up from a volcanic vent, piling up around the vent in the shape of a cone with a central crater....
s of scoria can be left behind after eruptions, usually forming mountains with a crater at the summit. An example is Mount Wellington, Auckland

Mount Wellington, Auckland

Mount Wellington is a peak and a suburb in Auckland City, New Zealand...
in New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses , and numerous Islands of New Zealand, most notably Stewart Island/Rakiura and the Chatham Islands....
, which like the Three Kings

Three Kings, New Zealand

Three Kings refers to both a suburb of Auckland, New Zealand, and the three-peaked volcano that it is named after. Three Kings should not be confused with the Three Kings Islands, located off the northern tip of New Zealand's North Island....
Mount in the south of the same city has been extensively quarried. Quincan, a unique form of Scoria, is quarried at Mount Quincan

Mount Quincan

Mount Quincan is a Volcano near Yungaburra, Queensland on the Atherton Tableland in Far North Queensland Queensland, Australia.Quincan, a type of Scoria, is mined from the south west quadrant of the mountain....
in Far North Queensland

Far North Queensland

Far North Queensland, or FNQ, is the northernmost part of the Australian States and territories of Australia of Queensland. The region, which contains a large section of the Tropical North Queensland area, stretches from the city of Cairns, Queensland north to the Torres Strait....
, Australia

Australia

Australia, officially the Commonwealth of Australia, is a country in the southern hemisphere comprising the Australia of the world's smallest continent, the major island of Tasmania, and numerous list of islands of Australia in the Indian Ocean and Pacific Oceans....
.

The quarry of Puna Pau

Puna Pau

Punau Pau is a quarry in a small crater or cinder cone on the outskirts of Hanga Roa in the South West of Easter Island . Puna Pau also gives its name to one of the seven regions of the Rapa Nui National Park....
on Rapa Nui/Easter island

Easter Island

Easter Island is a Polynesian island in the southeastern Pacific Ocean, at the southeastern most point of the Polynesian triangle. The island is a special territory of Chile....
was the source of a red coloured scoria

Scoria

Scoria is a textural term for Vesicular texturevolcanic rock. It is commonly, but not exclusively, basaltic or andesite in composition. Scoria is light as a result of numerous macroscopic ellipsoidal vesicles, but most scoria has a specific gravity greater than 1, and sinks in water....
which the Rapanui

Rapanui

The Rapanui or Rapa Nui are the native Polynesian culture inhabitants of Easter Island in the Pacific Ocean . Today, Rapanui people make up 60% of Easter Island's population....
people used to carve the Pukao (or top knots) for their distinctive Moai

Moai

'Moai' are monolithic human figures carved from rock on the Polynesian island of Rapa Nui between 1250 and 1500 Common Era. Nearly half are still at Rano Raraku, the main moai quarry, but hundreds were transported from there and set on stone platforms called Easter Island#Ahu around the island's perimeter....
from.

Reticulite ("thread-lace scoria") differs from scoria in being considerably less dense. It is formed from a thin layer of froth occurring on some basaltic lava flows due to the bursting of vesicle walls. The thin glass threads are the intersections of burst vessicles. This is the lightest rock on earth with its specific gravity

Specific gravity

Specific gravity is defined as the ratio of the density of a given solid or liquid substance to the density of water at a specific temperature and pressure, typically at 4?C and , making it a dimensionless quantity ....
less than 0.3. The delicate framework of thread-lace scoria is so open that the average porosity

Porosity

Porosity is a measure of the void spaces in a material, and is measured as a fraction, between 0?1, or as a percentage between 0?100%. The term is used in multiple fields including ceramics, metallurgy, materials, manufacturing, earth sciences and construction....
is 98-99%.

Scoria

How it is formed

See also