Veins quartz, grasin and pegmatite containing minerals of
tin and tungsten occurs along the length of Myanmar from south to north. In all
these areas, the occurrences of these mineral veins are closely associated with
the intrusions of coarse grained biotite granite which constitute apportion Ranges
in the Indo-Malayan mountain system. The granite bosses are distributed in the
eastern half of Myanmar starting from Kawthaung the southern most extremity,
wide-spreading abundantly in Mergui and Tavoy districts, Mokpalin, Yamethin and
Kyaukse districts. To the East the occurrence is traced in Kayah State and
western part of Shan State adjunct to Pyinmana Township. The mineralization of
Tin and Tungsten are found in or around the intrusions. These minerals occur in veins of quartz,
greisens and pegmatite that traverse the granite bodies and the adjoining
sedimentary rocks. Sometimes the constitute accessory minerals of some portion
of granite. The denudation of these primary deposits produces eluvial deposits near
the sources and alluvial deposits at distance places from the sources.
1. Primary Deposits
a.
Quartz veins and stringers traversing the granite and sedimentaries.
b. Decompossed
pegmatites containing muscovite and tourmaline and
c. as a
sergregation in greisens.
2. Secondary Deposits
d.
Elluvial deposits on the slopes of hills near the primary deposits
e.
Stream deposits and alluvial flats
f.
Deposits along the lower courses of the river.
Greisen bands are found are formed at the contact of quartz
vein and the granite. The mineral constituents of the veins are cassiterite,
wolframite, and other sulphide minerals such as pyrites, chalcopyrite,
arsenopyrite, molybdenite, stibnite and galenite. Generally, more
mineralization is found in thinner veins, sometimes, huge quartz veins and
pegmatite veins are practically barren. The portion of tin and wolfram varies
with the locality. But generally, the content tin decreases and that of wolfram
increases with the approach to the north.
The Mawchi Mine
The Mawchi mine is located at Latitude 18º 49’
24.8”N and Longitude 97º 9’ 22.1”E in the Balhke Destrict, Hparsaung Township,
Kayah State, Myanmar. It is situated 95 miles from south of Loikaw in Kayah
State, at elevation of 3000 feet. The mine is round about 19 miles from
Hparsaung and is situated in the Hilly region. It lies on one inch topographic
map sheet of 94 F/1. The existence of the occurrence is known since the last
100 years. Several technologist had estimated the reserves from 500,000 to
700,000 tons of ore with an average content of 1 to 2% tin and wolfram.
A coarse-grained biotite granite had intruded the
sedimentary rocks which were metamorphosed and termed as Mawchi series. There
are the argillites, sandstone and limestone. The intrusion of granite causes
the tourmalinisation of granite itself the formation of quartz veins carrying
wolfram and tin and tourmalinisation of adjoining country rocks. About 70
quartz veins containing ore minerals are known to occur in the area striking
from north to south and dipping vertical. These veins ate from a few inches to
8.37 feet wide and occur both in granite and the adjoining sedimentaries. Through, G.V Hobson assumed that the Mawchi
limestone is a limit of the northern extension of the veins, U Kyaw Nyein has
reported the northern continuation of these veins beyond the limestone in 1963.
He also traced the considerable occurrence of alluvial cassiterite along the
down stream of Kempyu village.
Mining is tributie system and underground methods. The
average annual production in the post war ranges to about 30 tons concentrate
of 60% tin. The mineralization could possibly occur at Sawalo and Khodogale on
the north and Parsalo, Mosaki and Sawkokedo on the south. The property is being
operated by by Mineral Development Corporation since January, 1963. At present,
the mine production was continued by M.E.H.Company, Myanmar.
Produce From: Review of Tin and Tungsten deposits of Myanmar. (U Tin Aye and U Kyaw Nyein
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