Sekaninaite ((Fe
+2,Mg)
2Al
4Si
5O
18) is a
mineralA mineral is a naturally occurring solid formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties. A rock, by comparison, is an aggregate of minerals and/or mineraloids, and need not have a specific...
which has historically been known to occur only in one locality - in Dolni Bory in
MoraviaMoravia is a historical region in central Europe in the east of the Czech Republic, one of the former Czech lands. It takes its name from the Morava River which rises in the northwest of the region.-Geography:...
. Until 1968 it was mistaken for
cordieriteCordierite or iolite is a magnesium iron aluminium cyclosilicate. Iron is almost always present and a solid solution exists between Mg-rich cordierite and Fe-rich sekaninaite with a series formula: 2Al3 to 2Al3...
. It was named after a
CzechThe Czech Republic is a country in Central Europe that is sometimes considered to be Eastern European. The country borders Poland to the northeast, Germany to the west and northwest, Austria to the south and Slovakia to the east. The capital and largest city is Prague...
mineralogist, Josef Sekanina. Next to
brazilianiteBrazilianite, whose name derives from its country of origin, Brazil, is a typically yellow-green phosphate mineral, most commonly found in phosphate-rich pegmatites...
and
bukovskyiteBukovskyite is an iron arsenate sulfate mineral with formula: Fe2·7 which forms nodules with a reniform surface. Under a microscope, these nodules appear as a collection of minute needles similar to gypsum...
, sekaninaite is probably the only other newly discovered mineral which appears in fairly substantial quantities and therefore has great interest for collectors.
It appears in the form of imperfect, large
crystalsA crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is crystallography...
and in coarsely granular or compact aggregates of a violet or grey-blue colour, which tend to turn green or yellow through the effects of weathering. Like cordierite, sekaninaite also alters into different types of mica, chiefly into
muscoviteMuscovite is a phyllosilicate mineral of aluminium and potassium with formula KAl
22, or
236...
. Some forms used to be described misleadingly as pinite (after the deposit of cordierite
pseudomorphIn mineralogy, a pseudomorph is a mineral or mineral compound that appears in an untypical form , resulting from a substitution process in which the appearance and dimensions remain constant, but the original mineral is replaced by another...
s from the
PiniPini is a surname, and may refer to:*Antonio Pini-Corsi*Carolina Pini*Rodolfo Pini*Ryan Pini*Wendy and Richard Pini, creators of the Elfquest series...
mine near
SchneebergSchneeberg is a town in Saxony’s district of Erzgebirgskreis. It has roughly 16,400 inhabitants and belongs to the Town League of Silberberg . It lies 4 km west of Aue, and 17 km southeast of Zwickau.- Location :...
in
GermanyGermany , officially the Federal Republic of Germany , is a country in Central Europe. It is bordered to the north by the North Sea, Denmark, and the Baltic Sea; to the east by Poland and the Czech Republic; to the south by Austria and Switzerland; and to the west by France, Luxembourg, Belgium,...
) or as gigantolite (because it forms pseudomorphs after the gigantic crystals of cordierite). Similar pseudomorphs occur in several localities in the Czech Republic, particularly near
JihlavaJihlava is a city in the Czech Republic. Jihlava is a centre of the Vysočina Region, situated on the Jihlava river on the ancient frontier between Moravia and Bohemia, and is the oldest mining town in the Czech Republic, ca. 50 years older than Kutná Hora.Among the principal buildings are the...
and by
DylenDyleň is a mountain in the Karlovy Vary Region of western Bohemia, located roughly from the Czech Republic–Germany border. At above sea level, its summit is the second highest peak in the Upper Palatinate Range ....
in the
Bohemian ForestThe Bohemian Forest is a low mountain range in Central Europe. Geographically, the mountains extend from South Bohemia in the Czech Republic to Austria and Bavaria in Germany. They create a natural border between the Czech Republic on one side and Germany and Austria on the other...
. But they are altered to such a degree that it is impossible to determine whether sekaninaite or cordierite was the original material.
PegmatiteA pegmatite is a very coarse-grained, intrusive igneous rock comprised of interlocking grains usually larger than 2.5 cm in diameter; such rocks are referred to as pegmatitic....
in contact with
gneissGneiss is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from pre-existing formations that were originally either igneous or sedimentary rocks. Gneissic rocks are usually medium to coarse foliated and largely recrystallized but do not carry large...
es of
sedimentarySedimentary rock is the type of rock that is formed by sedimentation of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....
origin (
paragneisses) are the parent rock of sekaninaite. Sekaninaite has also recently been discovered in
Japanis an island country in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, People's Republic of China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
.