Vol. 54.] CHLORITOID FROM KIKCARBINESHIEE. 149 



10. On the Occurrence of Chloritoid in Kincardineshire. By 

 George Barrow, Esq., F.G.S. (Read January 19th, 1898.) 



[Communicated by permission of the Director-General of 

 H.M. Geological Survey.] 



In the neighbourhood of Drumtochty, near Pordun, I found 

 numerous fragments of a green schist, which are characterized by 

 white or yellowish spots. On closer examination these specimens 

 disclose numerous minute, dark, glistening crystals, which are fairly 

 evenly distributed. Several of these were picked out with the 

 point of a knife, when they proved to be hard and brittle. Placed 

 on a sheet of white paper, the crystals were seen to be rudely hexa- 

 gonal and dark green by transmitted light. Their characters and 

 mode of occurrence suggested that they were chloritoid, or ' brittle- 

 mica,' and subsequent investigation has proved that this is their 

 true nature. 



The rock containing them was first met with in situ, at the 

 entrance to the little gully at the head of Friar Glen Burn, near 

 Drumtochty Castle. The section here shows a highly chloritic 

 green grauwacke, becoming* gradually finer in texture, and passing 

 into the spotted green schist containing the chloritoid, which may 

 be conveniently called the ' chloritoid-rock.' A few inches of grey, 

 almost metallic-looking schist succeeds this, and farther on is a 

 rather yellow schist, with small crystals of brown mica. This 

 passes gradually into a schistose pebbly grit of the arkose type : 

 that is, the pebbles are embedded in what was originally a fine 

 arkose matrix, as distinguished from the chloritic matrix of the 

 green grauwacke. This sequence of rocks is easily recognized, 

 and we have now succeeded in finding it in a number of localities 

 along a narrow belt of ground nearly 22 miles long, extending from 

 the coast north of Stonehaven nearly to the North Esk, keeping 

 always some little distance north of the Highland Eault. The 

 various localities will be indicated on the Geological Survey 1-inch 

 maps, sheets 66 and 67, to be shortly issued. 



Of these other exposures, the two most interesting are the section 

 seen in the Cowie Water, close to TJrie House, and that on the coast, 

 2 miles north of Stonehaven (Red Man, on the 1-inch map). These 

 are practically identical, and in both we note a thin film of grey 

 schist in contact with the coarser part of the green grauwacke. In 

 this film occur the largest crystals of chloritoid that have been found 

 hitherto in this district ; but they are very sparsely scattered through 

 the schist. With this exception, the chloritoid seems to be restricted 

 to the green band lying between the two grits referred to above. This 

 band varies much in appearance, and judging from the amount of 

 metamorphism that it has undergone, it may be a slate, phyllite, 

 or fine schist. 



It is in the fine schist alone that the chloritoids are visible in hand- 

 specimens ; their presence was, however, suspected in the slate and 

 fine phyllite, both from the nature of the section exposed and from 

 Q. J. G. S. No. 214. M 



