Aenigmatite, also known as ''Cossyrite'' after Cossyra, the ancient name of

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 ...

, is a

sodium Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable iso ...

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 ...

titanium Titanium is a chemical element with the symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resistant to corrosion in ...

inosilicate Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. In mineralogy, silica (silicon dioxide, ) is usually consid ...

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. ( ...

. The chemical formula is Na₂Fe²⁺₅TiSi₆O₂₀ and its structure consists of single tetrahedral chains with a repeat unit of four and complex side branches. It forms brown to black

triclinic 180px, Triclinic (a ≠ b ≠ c and α ≠ β ≠ γ ) In crystallography, the triclinic (or anorthic) crystal system is one of the 7 crystal systems. A crystal system is described by three basis vectors. In the triclinic system, the crystal is ...

lamellar crystals. It has

Mohs hardness The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by th ...

of 5.5 to 6 and

specific gravity Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water (molecule), wa ...

of 3.74 to 3.85. Aenigmatite forms a solid-solution series with wilkinsonite, Na₂Fe²⁺₄Fe³⁺₂Si₆O₂₀. Aenigmatite is primarily found in

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 ...

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 ...

pegmatite A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than and sometimes greater than . Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic com ...

s, and

granite Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...

s as well as silica-poor

intrusive rock Intrusive rock is formed when magma penetrates existing rock, crystallizes, and solidifies underground to form ''Igneous intrusion, intrusions'', such as batholiths, dike (geology), dikes, Sill (geology), sills, laccoliths, and volcanic necks.I ...

s. It was first described by

August Breithaupt Johann Friedrich August Breithaupt (May 16, 1791 – September 22, 1873) was a German mineralogist and professor at Freiberg Mining Academy in Freiberg, Saxony. Biography He was born in Probstzella. He received his doctorate at the Universities ...

in 1865 for an occurrence in the

Ilimaussaq intrusive complex The Ilimaussaq intrusive complex is a large alkalic layered intrusion located on the southwest coast of Greenland. It is Mesoproterozoic in age, about 1.16 Ga. It is the type locality of agpaitic nepheline syenite and hosts a variety of unusual ...

of southwest

Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland is t ...

. Its name comes from αίνιγμα, the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

word for "riddle". It was also reported from the

Kaidun meteorite Kaidun is a meteorite that fell on 3 December 1980 on a Soviet military base near what is now Al-Khuraybah in Yemen. A fireball was observed travelling from the northwest to the southeast, and a single stone weighing about was recovered from a s ...

, possibly a

Mars meteorite A Martian meteorite is a rock that formed on Mars, was ejected from the planet by an impact event, and traversed interplanetary space before landing on Earth as a meteorite. , 277 meteorites had been classified as Martian, less than half a percen ...

, which landed in March 1980 in

South Yemen South Yemen ( ar, اليمن الجنوبي, al-Yaman al-Janubiyy), officially the People's Democratic Republic of Yemen (, ), also referred to as Democratic Yemen (, ) or Yemen (Aden) (, ), was a communist state that existed from 1967 to 19 ...

. Other notable studied occurrences include: * Narsaarsuk and elsewhere in Greenland. * The Khibiny and Lovozero alkaline massifs on

Kola Peninsula sjd, Куэлнэгк нёа̄ррк , image_name= Kola peninsula.png , image_caption= Kola Peninsula as a part of Murmansk Oblast , image_size= 300px , image_alt= , map_image= Murmansk in Russia.svg , map_caption = Location of Murmansk Oblas ...

Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

. * The

Yenisei Range The Yenisey Range (russian: Енисейский кряж) is a range of mountains in Siberia. Administratively the range is part of the Krasnoyarsk Krai of the Russian Federation. The nearest town is Severo-Yeniseysk. The mountains have granite ...

Krasnoyarsk Krai Krasnoyarsk Krai ( rus, Красноя́рский край, r=Krasnoyarskiy kray, p=krəsnɐˈjarskʲɪj ˈkraj) is a federal subject of Russia (a krai), with its administrative center in the city of Krasnoyarsk, the third-largest city in Siber ...

. * The volcanic island of

Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical re ...

. * In the US, from Granite Mountain, near

Little Rock ( The "Little Rock") , government_type = Council-manager , leader_title = Mayor , leader_name = Frank Scott Jr. , leader_party = D , leader_title2 = Council , leader_name2 ...

Pulaski County, Arkansas Pulaski County is located in the U.S. state of Arkansas with a population of 399,125, making it the most populous county in Arkansas. The county is included in the Little Rock–North Little Rock– Conway metropolitan area. Its county seat is L ...

, and

Santa Rosa Santa Rosa is the Italian, Portuguese and Spanish name for Saint Rose. Santa Rosa may also refer to: Places Argentina *Santa Rosa, Mendoza, a city * Santa Rosa, Tinogasta, Catamarca * Santa Rosa, Valle Viejo, Catamarca * Santa Rosa, La Pampa * S ...

Sonoma County, California Sonoma County () is a county (United States), county located in the U.S. state of California. As of the 2020 United States Census, its population was 488,863. Its county seat and largest city is Santa Rosa, California, Santa Rosa. It is to the n ...

. * In Australia, from Warrumbungle volcano, Nandewar volcano, and the Mount Warning complex, New South Wales; and the Peak Range Province, Queensland. * In Canada, from

Mount Edziza Mount Edziza is a stratovolcano in the Stikine Country of northwestern British Columbia, Canada. The volcano and the surrounding area are protected within Mount Edziza Provincial Park. It consists of multiple peaks and ridges, with several gla ...

, the Ilgachuz and Rainbow Range shield complexes. * From Logan Point quarry, Dunedin volcano, New Zealand.

References

{{Titanium minerals Sodium minerals Iron(II) minerals Titanium minerals Inosilicates Triclinic minerals Minerals in space group 2