The Mines and Minerals of Lavrion - Aeschynite-(Y)Last Updated: 25th Jan 2019
By Branko Rieck
AESCHYNITE-(Y), (Y,Ln,Ca,Th)(Ti,Nb)2(O,OH)6, othorhombicGeneral Appearance
Crystals of Aeschynite-(Y) appear thin and lathlike. They are dark brown with a resinous luster. It reaches about half a millimeter in length. The single crystal used for identification with SXRD was also analyzed with SEM-EDS and INAA to confirm the Yttrium-dominant variety.
At a location discovered by the famous Greek collector Stathis Lazaridis (Lazaridisite) in the Plaka Mine #80 it was discovered, soon to be followed by an occurrence in the Plaka Porphyry Deposit (Uwe Kolitsch unpublished SEM-EDS results) and the cliffs at Legrena Cove .
Two of the localities where Aeschynite-(Y) could be identified are well-known for thin “alpinotype” veins (Plaka Mine #80 and Legrena Cove ). The paragenesis is basically the same with small quartz crystals, synchysite-(Ce), senaite, anatase, pyrite and calcite. The locality in the Plaka Mine #80 is special, as there are later, low temperature veins with stibnite and calcite crossing the host rock.
At the Plaka Porphyry Deposit it is found only as tiny grains (in the single digit micrometer range) grown in quartz with rutile, idiomorphic zircon and molybdenite.
Fig. 2: Aeschynite-(Y).
Fig. 3: Two euhedral, slightly zoned crystals of aeschynite-(Y) (bright), next to a distinctly prismatic, slightly zoned (due to variable traces of Nb and W) rutile crystal, a euhedral zircon crystal (bright grey), in a quartz-K-feldspar matrix.
SEM micrograph (BSE mode) of a polished section of a quartz sample with macroscopic molybdenite.
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