Plan view of the Kazennitsa
vein at the level 20 m (a) and its cross-section II-II (b).
biotite gneiss and schist;
fine- and middle-grained biotite granite (Yuzhakov complex);
allanite porphyry granite (Vatikha complex);
MORPHOLOGY AND STRUCTURE OF THE PEGMATITES.
The Kazennitsa vein occurs on the right bank of the Alabashka river in 900 m to the west-
northwest from the former Nizhnyaya Alabashka village and in 900 m to the east of the
Mokrusha vein (see Fig. 4). The vein is of plate shape with rare flexural bends. Its length is up to
150 m, its thickness is 0.5–1 m, with bulges up to 2–3.5 m. It strikes 330–340NW and dips at
40–80° to the northeast. This vein occurs in biotite gneiss hosting porphyry allanite granite and
biotite gneiss granite (Fig. 11). It has several apophyses forming three branches with smaller
The vein is asymmetrically zonal, there are three zones: (1) marginal zone (0.3–0.6 m) of bi-
feldspar pegmatite with coarse graphic K-feldspar, up to 5–15 cm annite laths, and medium-
graphic oligoclase replaced by spherulitic albite; (2) intermediate zone (0.2–0.7 m) of clearly
graphic bi-feldspar pegmatite with sword-shaped siderophyllite and typical coarser graphics in
the vein bulges; (3) central pegmatoid-blocky zone, with large crystals of K-feldspar, smoky
quartz, and muscovite, is better developed in the southern part of the vein (up to 1–1.5 m) where
K-feldspar crystals inside smoky quartz is up to 1.5 m, muscovite is up to 20 cm, green beryl is
up to 40 cm, and also there were up to 1 m druses of rock crystal with chlorite and limonite along
(19 x 7 x 6 cm,
weight 1520 g). Kazennitsa, Alabashka pegmatite field.
Neiva GPP collection. Collected: July 1993
Photo Michael B. Leibov
In vein, there are small shear joints. They are either subparallel to the contacts or diagonal. Their
opening is 0.5–3 cm, and they usually stop near the contact with vein and do not continue into
more ductile host rock.
Cavities occur in the pegmatoid-blocky and graphic zones, their number is more than 200, and
their size varies from first centimeters to 2–3 m along the vein forming up to 0.5 m wide empty
space (Fig. 12). The shape of these pockets is variable from sub-isometric to chink-shaped with
branches. The cavities contain druses of feldspar with quartz, muscovite, tourmaline, topaz,
beryl, and other minerals (beryl and topaz are recorded in 50% of the cavities). The total length
of gemstone productive part of the vein is 54 m.
Many minerals of this vein were multiply brecciated and dissolved; many of them were
regenerated with regrowth of multiple heads, change of shape, and sealing of fractures. The
dissolution was selective, because only one mineral was dissolved at a time or only selected
facets of crystals; sometimes several minerals were dissolved simultaneously, e.g., topaz, quartz,
and K-feldspar, but muscovite, albite, and tourmaline remained untouched. One of the cavities
after dissolution preserved only variously shaped and colored crystals of tourmaline which have
fallen on its floor. In some portions of the vein there are traces of intensive dissolution of quartz,
microcline, garnet, topaz, and beryl.
In general, the sequence of mineral formation in various zones of the vein was as follows:
(a) in marginal zone – orthoclase, oligoclase and albite, quartz, annite, magnetite;
(b) in intermediate zone – microcline, albite, quartz, siderophyllite, almandine, schorl, beryl;
(c) in blocky zone – microcline, albite, quartz, muscovite, almandine-spessartine, schorl, apatite,
beryl, topaz, brookite, andalusite, gahnite, zircon, xenotime, ferrotantalite, struverite;
(d) in the cavities of the blocky zone – microcline, albite, quartz, muscovite, elbaite, spessartine,
topaz, brookite, andalusite, gahnite, manganotantalite, cassiterite, microlite, hematite, goethite;
(e) late minerals in the cavities – muscovite, quartz, elbaite, foytite, topaz, milarite, calcite,
chabazite, stellerite, rutile, fluorite, kanonerovite, pyrrhotite, sphalerite, pyrite;
(f) hypergene minerals – vermiculite, montmorillonite, kaolinite, illite, goethite, psilomelane.
The Kazennitsa mine began production of beryl and aquamarine in the end of the 18th century.
By 1938, it was mined down to a depth of 10–14 m; after a new period of exploration works of
1987–91 and pilot mining in 1992–93 down to a depth of 30 m, it is considered to be exhausted.
In fact, the 20–30-m-thick vertical section of the steep-dipping Kazennitsa mine shows a wide
variation of the cavity minerals which often differ in paragenesis, shape, color of minerals,
sequence of crystallization, and dissolution phenomena that indicates a long functioning of the
open system during formation of pegmatite. This was a first steep-dipping vein whose druse
material does not exceed in beauty the lumps from Mokrusha.