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The Mines and Minerals of Lavrion - Wulfenite

Last Updated: 21st Sep 2018

By Branko Rieck

Wulfenite, Pb(MoO4), tetragonal



General Appearance
Wulfenite occurs as small crystals in open spaces in altered galena ore. It is not always easy to see the tetragonal symmetry as wulfenite belongs to one of the lower symmetrical tetragonal point groups and also appears as distorted crystals with one of the two a-axis elongated by a factor 3 or 4. It is generally orange in color, but variations from light yellow to a deep red have been observed. Generally, the crystals do not exceed 4 mm on edge, but maximum sizes up to 20 mm have been observed. The crystals grow on the matrix a singles or small groups. Nearly all crystals show the forms {001} and {103} (and their negative counterparts in this hemimorphic point group – which gives them a non-hemimorphic appearance). Rarer the forms {112} and {310} are seen. Very uncommon are crystals that show the forms {114} and {110}. Unfortunately, most crystals show internal fracturing to some extent. Crystals as clear and undamaged as the one in Fig. 13 are pretty rare.

Paragenesis
All localities in the Plaka area have in common that the wulfenite has formed in open spaces between heavily altered host rock and galena ore. Apart from iron oxides/hydroxides the paragenesis only has a handful of minerals and even less that are “collectible”. Mimetite, cerussite and calcite are the most common minerals accompanying wulfenite, along with various clay minerals. The most sought-after mineral being anglesite however.
The small locality “Spitharopoussi dumps” also yielded wulfenite along with other rare minerals, mainly arsenates. These discoveries came from material that was unearthed during a reforesting operation. Wulfenite here grows on quartz crystals and is most often together with mimetite. Usually this is all there is in the paragenesis. However, there are usually arsenate minerals like arsenotsumebite, duftite, carminite, arsenogorceixite and weilerite not too far away.

Localities
Most wulfenite hails from a small area within the Plaka mines. Localities are distributed among Adami #2 Mine (the most famous), Plaka #80 Mine and Plaka #145 Mine. The classical locality for wulfenite in Adami #2 is reached through a rather dangerous tunnel that passes by a very prolific area with native arsenic, silver minerals and Ca±Mg arsenates. For years the locality could not be reached, because the adit was flooded, but since 2014 the water has receded enough to pass by. As can be seen in the old photograph from 2007 (the last year before the flooding) the way is very dangerous, and the author considers the risk not worth the gain.
In the Plaka #80 mine there are at least two localities where wulfenite could be found. One is also well known for the vanadinite where the Czech scientist Dr. Ivan Prachař found a vug in the gossan matrix slightly above the vanadinite bearing layer containing numerous nice wulfenite crystals. Another find from the Plaka area comes from a connecting gallery from the Adami #2 mine to the Plaka #80 adit. Here the main focus of the collectors was mimetite, but some small wulfenite could also be had.
Finally, in Plaka #145 there is also an area targeted mainly at mimetite but yielding also some small wulfenite. This place was discovered by Vasilis Stergiou. A small find in 2010 at this locality yielded a very interesting paragenesis: orange-colored, skelettized and Molybdenum-rich stolzite on cerussit and yellow wulfenite.
We owe the knowledge of the occurrence of wulfenite in the Spitharopoussi area the sharp eyes of the former miner Kostas Tzanis (at the date of writing one of the few surviving miners who had actually worked in the fabled Kamariza mines when they were still in production). His find, and a handful of later discoveries, proved that wulfenite is not only found in Plaka area.


Fig. 1: This is a typical sample of the galena ore at the wulfenite locality in Adami #2. Thin veins of galena in heavily altered host rock. At one place at the border between the galena and the host rock a small vug with several wulfenite, mimetite and cerussite crystals has formed.


Fig. 2: Some wulfenite in situ. FOV: 70 cm


Fig. 3: The shiny movement surfaces recorded in the clay minerals also give due warning of the dangers of collecting at this place. Pieces quite adequately termed "coffin lid" quite regularly detach from the roof of the small working, burying everything in their path. The problem there: if they fall, they do so without the slightest prior warning.


Fig. 4: Access to the collecting area for wulfenite leads through a very dangerous tunnel.


Fig. 5: A specimen of wulfenite just recovered.


The following photographs show the wide variety in color of the Lavrion wulfenite.Fig. 6: Yellow wulfenite on mimetite


Fig. 7: orange


Fig. 8: orange


Fig. 9: red


Fig. 10: orange


Fig. 11: red


Fig. 12: Orange wulfenite showing the form {114} quite prominently, which is unusual at this locality.


Fig. 13: orange


Fig. 14: Wulfenite from a connecting gallery from the Adami #2 mine to the Plaka #80 adit


Fig. 15: This is one of very few known examples of wulfenite from Spitharopoussi. It is partially covered by yellow mimetite and rests on a matrix of small quartz crystals. FOV: 2 mm.







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Comments

Nice article and gorgeous photos!

Antoine Barthélemy
2nd Dec 2018 12:14pm
Thank you, Antoine!

I am grateful for all the beautiful photos uploaded by the members of the Mindat community. This makes it easy to write articles such as this.

Branko

Branko Rieck
3rd Dec 2018 12:00pm

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