576" SUPPLEMENT. 



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Lochs. " Most of the mineral spars are frequently 

 found shot into prismatical, cubic hexagonals, or 

 other figures. These figured crystals are gene- 

 rally transparent, and very beautiful. It is a great 

 curiosity to behold the inside of some of the large 

 cavities in which they are formed. These open 

 caverns are frequently met with in hard mineral 

 veins, and they are generally called by miners 

 lochs, or loch holes. 



" The miners know nothing of these cavernous 

 vacuities until they strike into them, as they ad- 

 vance in working ; and they are of various dimen- 

 sions, from the bigness of a nut, up to room 

 enough for three or four men to turn themselves in 

 them. 



" The magnitude of these caverns is generally 

 in some proportion to the capacity of the veins in 

 which they are found ; and the insides of them 

 frequently exhibit all the variety, beauty, and 

 splendour of the most curious grotto-work. 



" There is commonly a hajd concreted stony 

 crust, called druse, adhering to the inside of the 

 cavity ; out of which, as out of a root, an innu- 

 merable multitude of short prismatical crystals 

 are shot, which sparkle like a thousand diamonds 

 with the candle, or when brought up to the sun. 

 Between these clusters of mock diamonds, and 

 sticking to them promiscuously, there are often 



