Anatomy and categorization of pegmatites around Moragahakanda area
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Date
2001-11-16
Authors
Pitawala, A.
Journal Title
Journal ISSN
Volume Title
Publisher
University of Peradeniya, Peradeniya, Sri Lanka
Abstract
Pegmatitic occurrences are commonly observed in the proposed Moragahakanda-
reservoir area. Most of them are characterized by economically important minerals such as
quartz, feldspar and mica. At present, some pegmatites are mined for needs of the industry and
there is a surplus of raw materials. As a result, there has not been any serious attempt to
determine the extent and distribution of pegmatites.
Three types of pegmatite occurrences, which are genetically different from each other,
are observed. The older occurrences formed perhaps due to metamorphic events contain coarse
to very coarse grains (up to few ern) of quartz and feldspar as major minerals and amphibole
and mica as accessory minerals. They are smaller light coloured bodies several meters in
length. On the other hand, dark coloured pegmatites are characterized by coarse to very coarse
grains (up to several em) of pyroxene, amphibole and mica and they are occasionally
associated with dykes of pyroxenite. They occur as bands parallel to the general trend of
surrounding metamorphic rocks. The mineralogical composition and the filed relationship
suggest that these bodies had formed at greater depths, perhaps subsequent to a metamorphic
event. However, younger, strongly zoned pegmatites may have been formed at shallow depths.
They are mainly made up of mega size crystals (up to several meters) of quartz and feldspar.
The minor mineral constituent of the bodies is mica. Fluorite, tourmaline and opaque minerals
occur as accessory minerals.
Description
Keywords
Science , Anatomy , Pegmatites , Moragahakanda
Citation
Proceedings & abstracts of the Annual Research Sessions 2001,University of Peradeniya, Peradeniya, Sri Lanka,pp.149