of L^ad kills, Wanlockhead, and Glendinning. 401 



Asbestus. — This mineral was met with formerly in a vein called 

 Clanriscar vein, to the west of Susanna vein (Leadhills. ) It oc- 

 curs as a variety at Wanlockhead. Its fibres, instead of being pa- 

 rallel, are interwoven, (mountain leather;) its colour is yellowish- 

 white, and it is meagre to the touch. 



Arragonite. — This mineral is not mentioned by Jameson ; its 

 situation is not anomalous. La Perouse found the corraloid arra- 

 gonite in the cavities of decomposed sparry iron-ore, in the mines 

 of the Pyrenees. It is met with at Eisenerz, in Styria, &c. 



With respect to the ores, I may merely mention, that the brown 

 iron-ochre or hydroxide of iron, is, with quartz, the principal vein- 

 stone of Belton-grain at Wanlockhead, and of the lead glance vein 

 at Laguore, in the Pyrenees. The calamine which accompanies 

 lead glance and brown iron-ochre, in transition limestone, appears 

 to be a silicate. The carbonate of lead and the phosphate and ar- 

 seniate, with which the latter is generally associated, occur in most 

 metalliferous deposits containing lead. The sulphate is not so 

 common. Gray antimony ore is, according to Werner, of a middle 

 age. 



We were already aware, from the labours of Professor Jameson, 

 that the metalliferous veins of Leadhills and Wanlockhead occur 

 in a formation of greywacke and greywacke-slate. 



The term greywacke has been conferred, by the geognosts of the 

 Wernerian school, on every conglomerate and fragmentary or are- 

 naceous rock of transition formation that is anterior to the red 

 sandstone and coal formation, including Anagenites, or rounded or 

 oval parts of primitive rocks, with a schistose or talcose cement, 

 mimophyre, distinct grains of feldspar in an argillaceous paste, or 

 pisolitic fragments of schistose and slaty rocks. It has also fur- 

 ther been applied to schistose rocks, including the quartzoze, por- 

 phyroidal, and micaceous Phyllades of Alexander Brongniart. 



The term of greywacke slate has been used, as in the " ^line- 

 ralogical Description of the County of Dumfries," not as is usual 

 in oryctognostic geognosy, to denote the same rock assuming a slaty 

 structure, but as the geognostic application of all the schistose 

 rocks which accompany the greywacke formation ; as if clay-slate, 

 because it accompanies granite, should be called granite-slate. 



Considered in their utmost generalization, the range of transi- 

 tion rocks in which occurthemetalliferous veins of Leadhills, Wan- 

 lockhead, and Glendinning, consists of clay-slate, generally carbu- 

 retted or anthracitous, with subordinate beds of ampelite, lydian 

 stone, and flinty slate, greywacke and greywacke-slate, with beds 

 of compact feldspar and diorites, and a subordinate formation of 

 pitchstone. 



Clay -slate. — This rock is generally blackish-blue and carburet- 

 ted, is sometimes of an ash colour, or smoke-gray. Iii its vicinity 

 to greywacke, it is glimmering from intermixed scales of mica. It 

 is wrought in many places for the rooting of houses. 



