The Mines and Minerals of Lavrion - VanadiniteLast Updated: 25th Jan 2019
By Branko Rieck
Vanadinite, Pb5(VO4)3Cl, hexagonal
The mineral vanadinite usually occurs as short to long prismatic crystals. Most crystals show a pronounced basal pinacoid, however there have been rare occurrences of pyramidal terminations as well. The color ranges from pale yellow to an intense orange. Zonal growth is commonly observed with translucent off-white colored cores of vanadium-bearing mimetite surrounded by a (mostly thin) rim of orange vanadinite. The matrix consists of heavily altered host rock.
The source of vanadium has been debated and is as yet unclear. The close proximity to heavily altered mafic rocks may point to pyroxens and micas initially contained in these mafic rocks which are known – from less altered portions of the deposit – to contain vanadium in noticeable amounts. Vanadinite is a late stage secondary mineral that has grown in cavities in and on clear calcite crystals. A rare constituent of the paragenesis is dark brown crystals of arsendescloizite/descloizite solid solutions.
Currently there are three spots known for vanadinite in Lavrion. The most prominent being the one from which vanadinite was first discovered from Lavrion. It is a short working in the side of the Plaka #80 gallery. This locality has yielded nearly all of the vanadinite currently in the hands of collectors. While the “primary” source – a layer of rock about 20 cm thick, visible over a length of about 4 m – for vanadinite has been thoroughly mined out during 20 years of collecting, small crystals can still be found in the rubble.
Fig. 2: The short working in the Plaka #80 gallery. The band of white material to the left yielded the vanadinite. FOV: 3 m wide at the entrance and about 12 m deep.
In September 2012 the author discovered tiny vanadinite crystals while waiting for his colleagues at a connection between the Adami 2 adit and the Plaka #80 gallery. This connection is in parts hewn into the same type of rock that appears at the first occurrence of vanadinite. The crystals from Adami 2 adit are much smaller but otherwise can easily be mistaken for #80 specimens.
In April 2014 an occurrence of the now familiar rock type was encountered in the Adit #145 in Plaka. And again, vanadinite was discovered. In this locality the vanadinite is of the “arsenatian” variety, and actually most of the crystals are in fact vanadium-bearing mimetite. At this locality the crystals are zoned along the c-axis with orange vanadinite “bands” in nominally mimetite crystals. Most attractive are the crystals that have an orange “cap”.
Fig. 3: Tabular crystal of vanadinite from the #80 gallery. FOV: 3 mm.
Fig. 4: A milky white core of mimetite is covered by a narrow rim of brown vanadinite from the #80 gallery. The zonal growth occurred along the a-axis. FOV: 3 mm.
Fig. 5: Typical short prismatic crystal of vanadinite from the #80 gallery. FOV: 3 mm.
Fig. 6: Orange vanadinite from the Adami 2 occurrence. This is the best specimen I know from this locality. FOV: 2 mm.
Fig. 7: Arsenatian vanadinite from the Plaka #145 occurrence. Note the zonal growth along the c-axis between arsenatian vanadinite and a narrow band of almost As-free vanadinite. FOV: 3 mm.
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