First agardite-(Y), -(Nd), -(La) find in Bulgaria
Kunov, A.Y.; Nakov, R.A.; Stanchev, C.D.
published: Mar 7, 2002
The agardite from the Osenovlak deposit (indications data of Cu-porphyry and epithermal systems) has been found in small amounts among the zone of oxidation of altered and mineralized granodiorites and porphyritic diorites. Together with agardite supergene minerals are observed: malachite, azurite, chrysocolla, smithsonite, jarosite, seladonite, rozenite, cerussite, hemimorphite and romaneshite. Most often agardite associates with hemimorphite and romaneshite. Its color is bright green and forms radial aggregates up to 1-2 mm of rod-like crystals. They represent thin hexagonal prisms, elongated parallel . In the chemical composition Y, Nd, La, Eu, and Sm are present. At least three phases seem to exist: first, without Y, with domination of La and Eu (or Nd); second, with Y and different values of La and Nd; third, with dominating Nd, compared to Y and La. Ca is always present. The value of PbO is high (5.77 to 7.51wt.%), confirming previously published experimental data dealing with the crystal-chemical peculiarities of the mixite group (Olmi et al. 1991) and the role of Pb together with REE, Bi and Al.