24 MINERALOGY, 



and hard indurated slate abounding in siiex ; roof-slate, 

 and a variety that soils and writes like graphic slate. 



ROOFSLATE. 



In some localities, especially in one near the head waters 

 of a branch of Toung-byouk river, .he clay si ate cleaves 

 into large thin plates that would serve for roof slates, or for 

 slates to write upon. 



SHALE. 



Shale characterized as in " layers often uneven, pro- 

 tuberant, or knobby — often disintegrates and falls to 

 pieces," is abundant in the neighborhood of Maulmain, 

 and near the forks of the Tenasserim. 



BITUMINOUS SHALcI. 



Shale containing vegetable impressions, and carbonized 

 stems of plants, is found at the forks of the Tenasserim, 

 and perhaps belongs to the class of bituminous shales, 

 though it does not appear to contain much bitumen. 



GRAPHI* SLATE. 



A slate that " soils and writes, " as Dr. M'Clelland 

 described it, is found east of Tavoy, and another and softer 

 variety is found in Maulmain near Tremenheerite. They 

 may be justly regarded as varieties of graphic slate. 



SILICIOUS SLATE. 



Silicious slate is found near the granite mountains east 

 of Tavoy. By some it is denominated indurated slate. 



CLAYSTONE. 



There is a thick bed of reddish claystone, a few miles 

 east of Tavoy, that cannot be distinguished in hand 

 specimens from Scotch claystone. 



IRON CLAY. 



Iron clay is very abundant in the laterite, which is often 

 wholly composed of iron clay. 



