Dara-i-Pioz
Thanks to the author of the
article below and to László Horváth for his help.
The „plateau covered with onions“ - that´s what Dara-i-Pioz means, is
a very remote area located in the southern Tienshan Mountains close to the Pamirs
in Tadzhikistan. Dara-i-Pioz is the name of a river, a plateau, a glacier and
a pass. The area was first explored as late as in the 1920s-1930s and is still
under study.
The Dara-i-Pioz massif (sooner: massifs - the Upper and the Middle massif) mainly
consists of paleozoic alkaline granitoides, which penetrate metamorphic silurian
schists. A main feature of the granitoides is their high content of boron. The
most common accessory mineral is schorl, to a lesser degree axinite. The granitoides
are crossed by albite-aegirine-microcline metasomatites veins of up to 100 m,.
In these metasomatites there are extensive series of different, though mostly
alkaline, pegmatite veins of several cm to several m. Quartz-microcline-aegirine
pegmatites are most common. There are, however, some blocks of miaskitic nephelin-aegirine-feldspar
pegmatites, which seem to stem from alkaline intrusion that did not reach the
surface. The different rocks and minerals are to be found in blocks on and around
the glacier.
The mineralogical research started in the 1960s (Dusmatov and Alchasov). Geologically
and mineralogically there are similarities to Kola, Ilimaussaq and Mt.St.Hilaire.
Minerals containing boron are typical for this locality. Inclusions of e.g.
eudialyte and aegirine in quartz are characteristic. The mineralisation can
be divided into three types:
A:granitoides: subalkaline granodiorites with albite and microcline rich in
bor
B:coarse grained metasomatites
C:pegmatites
1a: quartz-microcline-pegmatites with astrophyllite, embedded in granite and
up to several cm thick
1b: pegmatites with coarse schorl and quartz, several dm thick
2a: aegirine-microcline-quartz pegmatites in
granitoides with steacyite, up to several m thick
2b: aegirine-quartz-microcline pegmatites in granites with hejtmanite and zektzerite,
up to several m thick
2c: quartz-aegirine-microcline pegmatites in granites close to metasomatites
with neptunite and zektzerite, up to several m thick
2d: quartz-aegirine-microcline pegmatites in granites with miserite - the most
interesting ones
3a: quartz cores, probably from broken 2d-pegmatites
3b: feldspar pegmatites blocks
3c: blocks of microcline and coarse grained reedmergnerite
As no surprise with the complicated geology the mineral list is quite long.
Mineral list (bold=type locality)
Aegirine
Aegirine-augite
Agrellite
Albite
Analcime
Andradite
Arapovite
Arfvedsonite
Astrophyllite
Autunite
Axinite-grp.
Bafertisite
Baoite
Baratovite
Bazirite
Berezanskite
Betafite
Biotite
Bismut
Calcioancylite-(Ce)
Calcite
Calcybeborosilite-(Y)
Cancrinite
Cappelenite-(Y)
Carbokentbrooksite
Danburite
Darapiosite
Datolite
Diopside
Dusmatovite
Eitelite
Ekanite
Eudialyte
Faizievite
Fluorapatite
Fluorapophyllite
Fluorite
Galena
Haiweeite
Hastingsite
Hedenbergite
Hejtmanite
Hyalotekite (probably a new h.-related mineral)
Kapitsaite-(Y)
Kentbrooksite
Kupletskite
Kupletskite-Cs
Leucophanite
Leucosphenite
Maleevite
Microcline
Milarite
Miserite
Mosandrite
Moskvinite-(Y)
Muscovite
Nalivkinite
Nepheline
Neptunite (and/or Manganneptunite)
Nordite-(Ce)
Osumilite
Pectolite
Pekovite
Polylithionite
Pyrochlore
Quartz
Reedmergnerite
Riebeckite
Rinkit
Schorl
Searlesite
Senkevichite
Shibkovite
Shortite
Sogdianite
Sokolovaite
Sphalerite
Steaceyite (doubtful, allegedly always turkesanite)
Stillwellite-(Ce)
Sugilite
Surkhobite
Tadzhikite-(Ce)
Tadzhikite-(Y)
Telyushenkoite
Tienshanite
Titanite
Turkestanite (co-type loc.)
Ursilite (?)
Willemite
Wollastonite
Zektzerite
Zeravshanit
Zirsilite-(Ce)
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&Suggested reading:
Belakowski,D.I.: Die seltenen Mineralien von Dara-i-Pioz im Hochgebirge Tadshikistans,
LAPIS, 16(1991), 12, pp.42-48
Kogarko,L.N., V.A.Kononova, M.P.Orlova, A.R.Woolley: Alkaline Rocks and Carbonatites of the World. Part 2: Former USSR. Chapman and Hall, London, 1995.
Reguir,EP et al.: The mineralogy of a unique baratovite- and miserite-bearing quartz albite aegirine rock from the Dara-i-Pioz complex, northern Takikistan. CANADIAN MINERALOGIST, 37(1999), 1369-1384