46 WYNNE: TRANS-INDUS SALT REGION, KOHAT DISTRICT. 



Two specimens of the dark-coloured beds, associated with the 

 gypsum, and smelling strongly of petroleum, examined at the Laboratory 

 of the Geological Survey by Mr. Tween, gave the following results : — 



Loss on heating 



Soluble 



Insoluble 



No. 1. 



Dark bituminous 



gypsous bed from Jatta 



Salt Quarries. 



100- 



No. 2. 



Dark bituminous shale 



with traces of gypsum 



Algad, between Muzduk- 



kai and Spina. 



5'6 



89-2 

 5 2 



100* 



The greater part of the soluble matter in No. 2 consists of carbonate 

 of lime. 



Impurities. — As a rule, the -gypsum is pure and homogeneous, the 

 only foreign matter observable in hand specimens being some gray clay, 

 crystals of iron pyrites, crystals of quartz, dolomite, or anhydrite in a 

 few places, and the bituminous ingredients of the black portions. 



The anhydrite just mentioned is rare, occurring in the form of very 

 small, but beautifully clear crystals, imbedded in the lowest stratum of 

 the gypsum just above the main mass of the salt at Saya Malgeen 

 (Seya Malgin) . 



Alum shale.— Associated with the gypsum in the eastern side of the 

 district are one or more bands of black alum shale, so charged with 

 pyrites as to have formerly induced their being worked for sulphur, 

 which occurs native in small quantities, the result, apparently, of 

 chemical reaction going on at the places where the shale occurs, and from 

 which sulphurous gases emanate. The rock, too, is frequently coated 

 with alum to such a degree as to affect one's skin in handling it. * 



* Dr. Verchere suggests that alum shale in a neighbouring district is a product of the 

 metamorphosis of lignite, but does not describe the process (paper previously quoted, p. 27). 



( 150 ) 



