The Mines and Minerals of Lavrion - Agardite-(Y)Last Updated: 22nd Oct 2019
By Branko Rieck
AGARDITE-(Y), YCu6(AsO4)3(OH)6 · 3H2O, hexagonal
Please also note the general remarks here!
Crystals of Agardite-(Y) appear as thin hexagonal crystals, that are usually found in radial sprays. Their color ranges from white to blue-green while geen shades are rarer but do exist. Color is not a distinguishing feature of agardite-(Y)! It can easily be confused with Goudeyite and Zálesíite. Plumboagardite due to its scarcity and Mixite due to its characteristic paragenesis are both less prone to be confused with agardite-(Y).
Agardite-(Y) differs from the other minerals of the agardite group as it occurs always in the paragenesis of aurichalcite. Other accompanying minerals include natroalunite, calcite, zincowoodwardite, smithsonite, hydrozincite, adamite and clay minerals. In contrast to the other agardite minerals it is usually grown directly on marble or on early, thin films of iron oxyhydrates, clay minerals and calcite that are in turn grown directly on the host rock.
Apart from finds at the Kamariza Dump, agardite-(Y) occurs to my knowledge only at two localities, one at the 4th level of the Hilarion area and one at the 2nd level of the Christiana area.
The most productive place no doubt is the Hilarion area which has yielded great specimens on a worldwide scale. Fractures in the marble host rock are either covered with aurichalcite or agardite-(Y) or both. Analysis of agardite-(Y) from this locality shows, that the A site in the crystal structure is almost exclusively occupied by Y (~70%) and Ca (~25%). The sum of the other REE is generally less than ~3%.
Fig. 1: The locality for agardite-(Y) at the 4th Level of the Hilarion area. Backback in foreground for scale.
Fig. 2: Agardite-(Y) on platy aurichalcite from the 4th level of the Hilarion area.
Fig. 3: Agardite-(Y) with calcite from the 4th level of the Hilarion area.
Fig. 4: Agardite-(Y) from the 4th level of the Hilarion area.
Fig. 5: Agardite-(Y) on platy aurichalcite.
Fig. 6: Agardite-(Y) with platy aurichalcite from the 4th level of the Hilarion area.
Fig. 7: Agardite-(Y) from the 4th level of the Hilarion area.
Fig. 8: Agardite-(Y) from the 4th level of the Hilarion area.
Fig. 9: Agardite-(Y) from the 4th level of the Hilarion area.
Thanks go to Dr. Uwe Kolitsch for constructive comments and diligent proofreading to improve this article.
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