Naslov
Distribution of thallium and ore genesis at the Crven Dol locality in Alšar.
(Distribution of thallium and ore genesis at the Crven Dol locality in Alšar)

Autori
Balić Žunić, Tonči ; Stafilov, Trajče ; Tibljaš, Darko

Izvornik
Geologica Macedonica (0352-1206) 7 (1993); 45-52

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
thallium; distibution; ore genesis; Alšar mine

Sažetak
Crven Dol lies at the northern end of the Alšar deposit and, according to the general geological situation, represents the uppermost part of the body of ore with the lowest temperature of formation. The mineralogical and petrological investigations show pronounced oxidation effects at this locality. An inf1uence of oxygenated meteoric waters was already present during the hydrothermal stage. Later on, it continued with the final formation of jarositic minerals. The first product of the hydrothermal solution was a transformation of dolomite in to ankerite. The first minerals deposited from solutions were siderite, pyrite and marcasite in a fine grained mixture. With a drop in temperature, realgar followed. Some of the realgar crystals include oxidation products (pharmacosiderite). When the temperature reached the stability field of lorandite, it appeared in a mixture with realgar. This was the last and the main stage in the hydrothermal event, characterized by large and well developed crystals. The last minerals in veins are the products of the following oxidation of sulphides. The most important are amorphous iron sulphatearsenate and dorallcharite, TI-member of the jarosite group. The content of thallium in hydrothermal solutions was high during all the stages. The siderite-pyrite-marcasite mixture contains 0.5-0.6, and realgar 0.4-0.5 wt% Tl. The two processes of Tl concentration in the solid phase were active in the deposit at Crven Dol. One was the crystalization of lorandite, as the main hypogene Tl mineral. The other occurred during the supergene enrichment. when Tl preferentially concentrated in jarositic minerals. Pharmaeosiderite, which formed early, during the still active hydrotherms, contains 1.71 wt% Tl, and in dorallcharite Tl represents one of the main elements, being over 20 wt%.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

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