TAB. LXIX. 



ARGILLA durissima. 

 Scotch Corundum. 



Class 2. Earths. Order 1. Homogeneous. 

 Gen. 2. Argil. Spec. 8. Corundum. 



Gen. Char. Unctuous to the touch. Easily diffusible 

 in water. Adheres to the tongue. Spec. Grav. 

 2. Kirw. Combines difficultly with acids, form- 

 ing with most of them deliquescent salts, soluble 

 in borax. Bab. 



Spec. Char. Nearly pure argil, hardest of all mine- 

 rals except the diamond. Divisible parallel to a 

 rhomb, the angles of which are 86° 26'. 93° 34'. 



1 his curious substance was sent rne among other things 

 from a dealer at Aberdeen, under the name of Red Schorle 

 from Achen-door. I figure it here, because it is a substance 

 which appears to be new to British writers. Upon inquiry 

 I found it was very little known, nor was it to be found in 

 any mineralogical collection in London, nor scarcely in 

 Scotland. I therefore was glad to present a few of my 

 friends with it. Even Mr. Jameson had not previously ob- 

 tained it. From him I hope for a good account of it. 

 It occurs in long columns or bars from an eighth to three 

 quarters of an inch thick, mostly confused, often diverging 



