Travertine,Building Materials

In the southwestern Pakistan, the deposits of travertine referred to as onyx marble are widely distributed in the Eruptive Zone of Balochistan Basin. Travertine is of excellent quality, highly priced and has been a major export mineral commodity in the past. Travertine deposits occur in the area of Chagai.between Longitude 62°-65° east. Recent sand dunes in the desert, west of low hillocks often covered by overburden of travertine arc interbedded with volcanic rocks of Pleistocene age. The main deposits are located at Zeh, Tozghi, Mashki Chah, Butak, Patkok, Juhli, Anar Malmal and Zard Khan (Ahmed, 1965). Marketable reserves of travertine at all localities (except Zeh) are one million cubic metres plus an additional 0.5 million cubic metres of estimated reserves at Zeh, which have been calculated by using aerial photographs and with out ground check.

                Genetically, travertine is considered to be the result of hot-spring deposition related to the latest phase of volcanic activity in the long series of volcanic episodes that characterise the Eruptive Zone. Travertine appears to have been deposited in spring pools on an irregular topography and after subsequent erosion is now found as flat or gently dipping remnants situated as terrace deposits at many levels (Hunting Survey Corporation, 1961). The mineral forming travertine is calcite(Ahmad, 1965) banded in layers of various shades of green, yellow, red and white. Blocks of large size can be obtained. However, the bedding planes and interlayering of tuffs limit the thickness of the blocks (Ahmed, 1965).

               Poor quality small occurrences of travertine have recently been located in Laki Formation of

Eocene age in Thano Bula Khan area of southern Lower Indus Basin. Travertine occurs in caverns and cavities in the limestone formations.

               One of the factors in the development of a civilization is strongly protected shelter/home. Today we know the important ancient civilization by remnants of their homes and other buildings, e.g., ancient Egypt, Babylon and Persia. Although we have entirely different raw material from the ancient civilization yet it is as strong as those of ancient raw material and much cheaper too. Natural building material has truly quickened the establishment of long lasting civilizations. Rocks, gravels and sands are widespread in the country and are conveniently used for construction purposes. Gravels are generally obtained from stream beds in the foothill zone of the Indus Basin. The predominant rock type in the area being limestone serve as an excellent parent material to yield good quality gravel which can not be transported far from parent rock and is dumped in the stream beds and piedmonts. The finer sand particles are however carried to the plains, where they are generally deposited as point bars of rivers of the Indus drainage system. Sand deposits are also present along

the coastline beaches. Eolian sand deposits are widespread in the Thar and Balochistan deserts. Easy availability of unconsolidated sand from these sources renders it cheaper.

                Construction material represented by a large variety of rocks is available in the stratigraphic columns present near populated areas. To name a few better ones, examples, may be given of Parh Limestone, Pab Sandstone, Kirthar Limestone, Nari Sandstone etc., in Lower Indus Basin; Khewra

Sandstone Jutana Dolomite, Sakesar Limestone, etc., in Upper Indus Basin; granites of Nagar Parkar Indian Shield remnants; and slates, quartzites and granites of Northern Area can also be made available close to population.