203 



the form of niammilary encrustations of a chalky- or pipe-clay-like 

 aspect, but exhibiting traces of both radiate structure and lamellar, 

 concentric banding, due to deposition in successive coats. This is 

 one of the minerals that a careful search might bring to light in 

 the Caldbeck Fells, especially in the neighbourhood of Rowtin 

 Gill. 



Another mineral, even rarer still, is represented in the British 

 Museum by specimens from both the Alston district and Rowtin 

 Gill, in the Caldbeck Fells. This is Aurichalcite, or Green 

 Calamine, the Hydrous Carbonate of Zinc and Copper, represented 

 by the formula 2CuC -i- 3ZnH. Mr. Br}'ce Wright states (pp. cii.) 

 that this mineral is "found associated with Malachite at Rowtin 

 Gill in an extremely hard ochreous rock." The British Museum 

 specimens, which occur on saccharoidal quartz in association with 

 Linarite, are in the form of mammilary aggregations of minute 

 acicular crystals of a pale greenish-blue or turquoise tint, ranging 

 to nearly emerald green. The Alston specimens are small, and 

 they occur as velvety encrustations of a turquoise green colour. 



Malachite, Hydrous Copper Carbonate, has been mentioned 

 several times as occurring in various localities in the district under 

 consideration. Indeed, it may safely be stated that, wherever 

 copper ore in any form occurs, Malachite occurs as a decomposition- 

 product along with it Its bright verdigris-green, or emerald-green, 

 tint, is sure to attract attention, so that it is observed perhaps with 

 more frequency than almost any of the other ores. It varies in 

 form from mere stains, to thick encrusting masses, under a great 

 variety of circumstances ; but in every, or nearly every case, in 

 connection, direct or indirect, with faults. Like Galena, a mineral 

 it is often associated with, this ore occurs indiscriminately in either 

 the Carboniferous rocks, or in the older series beneath them. It 

 is not yet known — in this district, at all events — to occur in any 

 of the New Red, as it does at Alderly Edge in Cheshire, and 

 elsewhere. In the Carboniferous rocks it occurs, preferably, in 

 connection with limestone, at Clouds, Orton Scars, Harcla, Win ton, 

 Helton, and other places. In the Alston district it is not at all 

 rare; but in no case has it been found in very large quantities. It 



