Pantellerite is a type of
volcanic rock
Volcanic rock (often shortened to volcanics in scientific contexts) is a rock formed from lava erupted from a volcano. In other words, it differs from other igneous rock by being of volcanic origin. Like all rock types, the concept of volcanic r ...
, specifically a
peralkaline
Peralkaline rocks include those igneous rocks which have a deficiency of aluminium such that sodium and potassium are in excess of that needed for feldspar. The presence of aegerine (sodium pyroxene) and riebeckite (sodium amphibole) are indicati ...
rhyolite
Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral ...
. It has a higher
iron
Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...
and lower
aluminium
Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...
composition than
comendite
Comendite is a hard, peralkaline igneous rock, a type of light blue grey rhyolite. Phenocrysts are sodic sanidine with minor albite and bipyramidal quartz. Iddings, Joseph Paxson, 1913, ''Igneous rocks: composition, texture and classification'', ...
. It is named after
Pantelleria
Pantelleria (; Sicilian: ''Pantiddirìa'', Maltese: ''Pantellerija'' or ''Qawsra''), the ancient Cossyra or Cossura, is an Italian island and comune in the Strait of Sicily in the Mediterranean Sea, southwest of Sicily and east of the Tunis ...
, a volcanic island in the
Strait of Sicily
The Strait of Sicily (also known as Sicilian Strait, Sicilian Channel, Channel of Sicily, Sicilian Narrows and Pantelleria Channel; it, Canale di Sicilia or the Stretto di Sicilia; scn, Canali di Sicilia or Strittu di Sicilia, ar, مضيق ص ...
and the
type location for this rock. On Pantelleria the rock is usually found as a
vitrophyre Vitrophyre is a volcanic rock with a porphyritic texture in which larger crystals (phenocrysts) are embedded in a glassy groundmass
The matrix or groundmass of a rock is the finer-grained mass of material in which larger grains, crystals, or c ...
containing
phenocryst
300px, feldspathic phenocrysts. This granite, from the Switzerland">Swiss side of the Mont Blanc massif, has large white plagioclase phenocrysts, triclinic minerals that give trapezoid shapes when cut through). 1 euro coins, 1 euro coin (diameter ...
s of
anorthoclase
The mineral anorthoclase ((Na,K)AlSi3O8) is a crystalline solid solution in the alkali feldspar series, in which the sodium-aluminium silicate member exists in larger proportion. It typically consists of between 10 and 36 percent of KAlSi3O8 and ...
or
sanidine
Sanidine is the high temperature form of potassium feldspar with a general formula K(AlSi3O8). Sanidine is found most typically in felsic volcanic rocks such as obsidian, rhyolite and trachyte. Sanidine crystallizes in the monoclinic crystal system ...
.
Quartz
Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical form ...
is found only in the most strongly peralkaline rocks.
Mafic
A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include ...
mineral
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. ( ...
s may include
aegirine
Aegirine is a member of the clino pyroxene group of inosilicate minerals. Aegirine is the sodium endmember of the aegirine-augite series. Aegirine has the chemical formula Na Fe Si2 O6 in which the iron is present as Fe3+. In the aegirine-augit ...
,
fayalite
Fayalite (, commonly abbreviated to Fa) is the iron-rich end-member of the olivine solid-solution series. In common with all minerals in the olivine group, fayalite crystallizes in the orthorhombic system (space group ''Pbnm'') with cell para ...
,
aenigmatite
Aenigmatite, also known as ''Cossyrite'' after Cossyra, the ancient name of Pantelleria, is a sodium, iron, titanium inosilicate mineral. The chemical formula is Na2Fe2+5TiSi6O20 and its structure consists of single tetrahedral chains with a repe ...
,
ilmenite
Ilmenite is a titanium-iron oxide mineral with the idealized formula . It is a weakly magnetic black or steel-gray solid. Ilmenite is the most important ore of titanium and the main source of titanium dioxide, which is used in paints, printing ...
, and
sodic amphibole
Amphibole () is a group of inosilicate minerals, forming prism or needlelike crystals, composed of double chain tetrahedra, linked at the vertices and generally containing ions of iron and/or magnesium in their structures. Its IMA symbol is A ...
(often
arfvedsonite
Arfvedsonite () is a sodium amphibole mineral with composition: aNa2] Fe2+)4Fe3+(OH)2, Si8O22]. It crystallizes in the monoclinic prismatic crystal system and typically occurs as greenish black to bluish grey fibrous to radiating or stellate pr ...
or ferrorichterite).
White, J.C., Ren, M., and Parker, D.F., 2005, "Variation in mineralogy, temperature, and oxygen fugacity in a suite of strongly peralkaline lavas and tuffs, Pantelleria, Italy." The Canadian Mineralogist, vol. 43, 1331-1347.
/ref>
Occurrence
;North America
*Ilgachuz Range
The Ilgachuz Range is a name given to an extinct shield volcano in British Columbia, Canada. It is not a mountain range in the normal sense, because it was formed as a single volcano that has been eroded for the past 5 million years. It lies on ...
, west-central British Columbia
British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...
, Canada
*La Reforma
''La Reforma'' ( en, The Reform), refers to a pivotal set of laws, including a new constitution, that were enacted in Mexico during the 1850s after the Plan of Ayutla overthrew the dictatorship of Santa Anna. They were intended as modernizing m ...
, Baja California Peninsula, Mexico
*Level Mountain
Level Mountain is a large volcanic complex in the Northern Interior of British Columbia, Canada. It is located north-northwest of Telegraph Creek and west of Dease Lake on the Nahlin Plateau. With a maximum elevation of , it is the second-hig ...
, northwestern British Columbia, Canada
;Antarctica
*Mount Berlin
Mount Berlin is a high glacier-covered volcano in Marie Byrd Land, Antarctica, from the Amundsen Sea. It is a mountain with parasitic vents that consists of two coalesced volcanoes; Berlin proper with the wide Berlin Crater and Merrem P ...
, Marie Byrd Land
Marie Byrd Land (MBL) is an unclaimed region of Antarctica. With an area of , it is the largest unclaimed territory on Earth. It was named after the wife of American naval officer Richard E. Byrd, who explored the region in the early 20th centur ...
*Mount Moulton
Mount Moulton is a complex of ice-covered shield volcanoes, standing east of Mount Berlin in the Flood Range, Marie Byrd Land, Antarctica. It is named for Richard S. Moulton, chief dog driver at West Base. The volcano is of Pliocene age and ...
, Marie Byrd Land
* Mount Noice, Victoria Land
Victoria Land is a region in eastern Antarctica which fronts the western side of the Ross Sea and the Ross Ice Shelf, extending southward from about 70°30'S to 78°00'S, and westward from the Ross Sea to the edge of the Antarctic Plateau. It ...
;Asia
*Udokan Plateau
The Udokan Plateau is a volcanic field in Transbaikalia, Russia. It covers a surface area of northeast of Lake Baikal in North Asia. Volcanism in the Udokan Plateau included both basaltic lava flows and later individual volcanic cones. Volcanism c ...
, Russia
;Africa
*Dabbahu Volcano
Dabbahu Volcano (also Boina, Boyna or Moina) is an active volcano located in the remote Afar Region of Ethiopia. This stratovolcano is part of the Afar Triangle (Afar Depression), a highly active volcanic region which includes Erta Ale. An erupti ...
, Afar Region
The Afar Region (; aa, Qafar Rakaakayak; am, አፋር ክልል), formerly known as Region 2, is a regional state in northeastern Ethiopia and the homeland of the Afar people. Its capital is the planned city of Semera, which lies on the pave ...
, Ethiopia
* Ma Alalta, Afar Region, Ethiopia
*Tat Ali
Tat Ali is a low Holocene shield volcano located in the northern part of the Afar Region of Ethiopia. This elevation is characterized as having an elongated summit depression that has produced a variety of rock types, ranging from basalts to pan ...
, Afar Region, Ethiopia
References
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Volcanic rocks