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ISSN 1075 7015, Geology of Ore Deposits, 2010, Vol. 52, No. 4, pp. 322–333. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © L.G. Filimonova, A.V. Sivtsov, N.V. Trubkin, 2010, published in Geologiya Rudnykh Mestorozhdenii, 2010, Vol. 52, No. 4, pp. 358–371.

Manganese Oxides and Associated Minerals As Constituents
of Dispersed Mineralization of Metasomatic Rocks
in the Dukat OreField
L. G. Filimonova, A. V. Sivtsov, and N. V. Trubkin
Institute of Geology of Ore Deposits, Petrography, Mineralogy, and Geochemistry,
Russian Academy of Sciences, Staromonetnyi per. 35, Moscow, 119017 Russia
Received August 28, 2009

Abstract—Lithiophorite and coronadite—varieties of vernadite and todorokite—make up finely dispersed
colloform mixtures along with minor grains andnanoparticles of aluminosilicates and ore minerals in meta
somatic rocks of the Dukat ore field, which were formed in local areas of fluid and hydrothermal solution dis
charge at the upper level of the ore forming system. Fe vernadite associates with feroxyhyte, magnetite, apa
tite, K feldspar, native silver, and acanthite in greisenized granitoids and with epidote, cerianite, plattnerite,
and Fechlorite in quartz–garnet–chlorite propylites. Todorokite with high Pb, Tl, and Sn contents associ
ates with epidote, albite, bitumen, and native silver in quartz–epidote–chlorite propylites. Al vernadite,
coronadite, and lithiophorite associate with opal, kaolinite, Fe chlorite, zincite, uraninite, native silver, and
acanthite in argillisites. These data allowed us to estimate the conditions ofmanganese accumulation in the
epithermal ore forming system and deposition conditions of Mn rich, finely dispersed mineral mixtures in
mineralized zones hosted in metasomatic rocks of the ore field.
DOI: 10.1134/S1075701510040069

INTRODUCTION
Manganese oxides make up diverse groups of min
erals, which differ in crystal structure, trace element
contents, and amount of water molecules.Anhydrous
oxides (braunite, jacobsite, hausmannite, etc.) are
characteristic of metamorphic and volcanosedimen
tary manganese, deposits, whereas hydrous oxides (pyro
lusite, todorokite–psilomelane, hollandite–cryptom
elane, vernadite, and ramsdellite groups) concentrate in
mantles of weathering and large sedimentary deposits
(Smirnov et al, 1981; Chukhrov et al., 1989; Yakhontova
and Zvereva,2000; Savko et al., 2007).
Subeconomic concentrations of manganese oxides
are characteristic of some types of epithermal silver–
base metal and gold–silver sulfide deposits localized
in continental rifts and grabens (Smirnov, 1955; Kon
stantinov et al., 2000). In Ag bearing orebodies, man
ganese oxides accompany Mn rich aluminosilicates:
spessartine, bustamite, tephroite, rhodonite, andpyroxmangite. Higher concentrations of manganese
oxides occur in oxidation zones of these deposits.
They are regarded as prospecting guides for silver–
base metal deposits located at a certain depth. Such
guides had been used for positive evaluation of the
area, where the unique Dukat Au–Ag deposit was then
discovered (Konstantinov et al., 1998).
On the basis of long term geological, mineralogical, and geochemical studies of the Dukat ore field, it
Corresponding author: L.G. Filimonova. E mail: flg@igem.ru.

is generally agreed that ore mineralization therein is
related to Cretaceous magmatic activity (Sidorov
et al., 1989; Konstantinov et al., 1998, 2002). The high
Mn contents in minerals of quartz–rhodonite orebod
ies are referred either to additional supply of manganese
fromvolcanosedimentary rocks or to possible regenera
tion of Ag bearing stratiform bodies hosted in Permian
manganous cherty and terrigenous rocks in the base
ment of the volcanic belt (Tomson et al., 2003).
Manganese oxides that make up finely dispersed
mineral mixtures with aluminosilicates and micro and
nanoparticles of ore minerals were revealed for the first
time during investigation of...