Limestone host
Limestones are very common host rocks for base metal sulphide deposits.
Ore is often developed in a small number of preferred beds or at certain
sedimentary interfaces (ɩɪɨɦɟɠɬɨɱɧɚɹ ɩɨɜɟɪɯɧɨɫɬɶ). These are often zones
in which the permeability has been increased by dolomitization or fracturing.
Argillaceous hosts
Shales (ɫɥɚɧɟɰ), mudstones (ɚɪɝɢɥɥɢɬ \ ɝɥɢɧɢɫɬɵɣ ɫɥɚɧɟɰ), argillites
(ɝɥɢɫɬɧɚɹ ɩɨɪɨɞɚ \ ɚɪɝɢɥɥɢɬ) and slates (ɚɫɩɢɞɧɵɣ ɫɥɚɧɟɰ) are important
host rocks for concordant orebodies. This deposit appears to be syngenetic,
and the lead, zinc and other metal sulphides form an integral part of the rocks
in which they occur. They are affected by sedimentary deformation. The
orebody occurs in a single generally conformable zone (ɫɨɝɥɚɫɧɨ
ɡɚɥɟɝɚɸɳɚɹ ɡɨɧɚ) between 60 and 90 m thick and runs 6.6% lead and 5.9%
zinc. Other metals recovered are silver, tin, cadmium, antimony, bismuth,
copper and gold. The footwall rocks consist of graded impure quartzites and
argillites and, in places, conglomerate. The hanging wall rocks are more
thickly bedded and arenaceous. The ore zone is a mineralized argillite in
which the principal sulphide-oxide minerals are pyrrhotite, sphalerite, galena,
pyrite and magnetite, with minor chalcopyrite, arsenopyrite and cassiterite.
Arenaceous hosts
Chalcopyrite is the principal sulphide mineral, sometimes being accompanied
by significant amounts of bornite. The ore zone consists of feldspathic
sandstone. The basal portion is coarse-grained and characterized by festoon
cross-bedding (ɝɨɪɢɡɨɧɬɚɥɶɧɚɹ ɫɥɨɢɫɬɨɫɬɶ) in which bornite is
concentrated along the cross-bedding together with well rounded, obviously
detrital zircon; whilst in other parts of the orebody, concentrations of
sulphides occur in the hollows of ripplemarks and in desiccation (ɭɫɥɵɯɚɧɢɟ
\ ɨɛɟɡɜɨɠɢɜɚɧɢɟ) cracks. These features suggest that some of the sulphides
are detrital (ɨɫɬɚɬɨɱɧɵɣ \ ɨɛɥɨɦɨɱɧɵɣ) in origin. Mineralization ends
abruptly at the hanging wall, suggesting a regression (ɨɬɫɭɬɩɥɟɧɢɟ) and at
this sharp cut-off (ɛɨɪɬɨɜɨɟ ɫɨɞɚɪɠɚɧɢɟ) the fades changes from an
arenaceous one to dolomites and shallow water muds.
Copper is not the only base metal that occurs in such deposits. Similar are
lead ores and silver deposits. Another important class of pore-filling deposits
is the uranium-vanadium deposits which occur mainly in sandstones of
continental origin but also in some siltstones and conglomerates. The
orebodies are very variable in form, and pods (ɭɞɥɢɧɟɧɧɚɹ ɥɢɧɡɚ) and