Preliminary Geology And Petrography Of Swat Kohistan

e made of the coarse grained, biotite-bearing dioritee to the north of Laikot and
in the Deshai area, and the coarse-grained mafic gneissea exposed in the stream
to the east of Madyan and the surrounding parts. The former in particular are
light coloured, homogeneous, massive, and will take a good polish.
In Deshaj area, some of the diorites have developed an orbicular texture,
with many, dark to lighter, shells. The shells are rounded to ovoid, reaching
over a foot in length; the individual shells usually having radiating minerals.
We think that these rocks can prove to be excellent material if cut into slabs
for table tops and frontal decoratione.
Dundai Marble : Near the village of Dudnai, two miles to the north of
Thakot bridge along the Indus Valley Road, local outcrops of marble are seen.
They are grey or white (with s greenish touch of serpentine at places) beds of
only a few feet thickness; the thickest one is 30-40 feet. Nearly all of them
pinchout in short distances of a few hundred yards or less. Many of them are
banded; besides grey and white, brownish and mixed-colour bands also occur.
The rocks are generally uniform in texture but many are fractured and only
small blocks (less than a foot-cube) can be extracted. However, in a five feet
thick bed, which has fewer fractures, many cubic feet large blocks are extractable.
Some of the marbles are micaceous and, in a few, iron oxide staining is
seen along the fractures. Thus, it is clear that the marbles at Dandai are not
of much economic interest although they can be locally used in chips and for
decorstion. The marble has been used in Thakot bridge. It will be worthwhile
to search for more of these marbles in the adjacent parts of Hazara Kohistan,
to the east of the Indus.
(b) Abrasive Materid.
In the area between Patan and Jijal, along the Indus River, garnet gneissea
are the most common rocka. Some of them have as much as 80% garnet,
besides plagioclase and ferromagneisan minerals. A rock with 10% garnet is
generally conaidered suitable for extracting abrasive garnet from. The high
quantity of ga.rnet in these rocks is thus encouraging and suggests that some of
these rocka may be cruehed and directly utilized for manufacturing low to
medium quality abrasives. A few of these rocks are fairly weathered, fractured,
with low crushing strength and not much energy will be used in grinding them.
However, for quality improvement, purification will be needed. In many
places of the world, where garnet is extracted for abrasive purposes, stresa is
hid on the size factor, i.e., the individual garnet grnina should not be less than
the size of a pea. In Swat, the garnebbearing rocks have much smaller grains.