The Mines and Minerals of Lavrion - Agardite-(Nd)Last Updated: 23rd Oct 2019
By Branko Rieck
AGARDITE-(Nd), CeCu6(AsO4)3(OH)6 · 3H2O, hexagonal
Please also note the general remarks here!
The type locality of this member of the agardite subgroup is a connecting tunnel between the 2nd and 3rd levels of the Hilarion area. The composition of the type material is [(Nd0.19La0.14Y0.12Pr0.05Gd0.02Ce0.02Sm0.02Dy0.02)Ca0.39]Σ0.97(Cu5.49Zn0.44)Σ5.93(AsO4)3(OH)5.38·2.64H2O (Pekov et al., 2011). The agardite-(Nd) crystals often have a core of zálesíite with peripheral parts of agardite-(Nd) and agardite-(La).
Fig. 1: The type locality of agardite-(Nd). For scale see the gloves in the foreground.
Crystals of Agardite-(Nd) appear as thin hexagonal crystals that are usually found in radial sprays, but occasionally also randomly scattered on the matrix or even filling vugs completely. Their color ranges from white to “blue-green”. Color is not a distinguishing feature of agardite-(Nd)! It can easily be confused with goudeyite and zálesíite. Plumboagardite due to its scarcity and mixite as well as agardite-(Y) due to their characteristic paragenesis are less prone to be confused with agardite-(Nd).
Agardite-(Nd) is quite often the only mineral in vugs in the gossan matrix. If not, Cu-bearing adamite is the most common mineral to accompany it, followed by conichalcite. Malachite and azurite are often seen in the vicinity, too. Quite a bit rarer are associations with other copper-bearing minerals like parnauite, brochantite, rosasite, and cornwallite.
Apart from finds at the Kamariza Dump, agardite-(Nd) occurs most prominently at the Hilarion and Christiana mines. The most productive places in the Hilarion area are concentrated at the 2nd and 3rd levels, while in the Christiana area the 1st, 2nd, and 3rd levels yield great specimen.
Fig. 2: Agardite-(Nd) from the type locality.
Fig. 3: Agardite-(Nd) from the type locality.
Fig. 4: On a base of tiny agardite-(La) later and somewhat bigger crystal sprays of agardite-(Nd) are grown. Both have nearly identical color. The big green crystals are copper-bearing adamite.
Fig. 5: Blue-green sprays of agardite-(Nd) and agardite-(La) from the type locality of agardite-(Nd). EMPA shows zoning from a core of agardite-(La) to a rim of agardite-(Nd). The big green crystals are copper-bearing adamite.
Pekov, I.V., Chukanov, N.V., Zadov, A.E., Voudouris, P., Magganas, A., Katerinopoulos, A. (2011) Agardite-(Nd), CeCu6(AsO4)3(OH)6 · 3H2O from the Hilarion Mine, Lavrion, Greece: mineral description and chemical relations with other members of the agardite-zálesíite solid-solution system. Journal of Geosciences: 56: 249-255.
Thanks go to Dr. Uwe Kolitsch for constructive comments and diligent proofreading to improve this article.
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