MODE IX. AMYGDALlTE. 



Perthshire. Moca-stones are also said to be 

 found on the banks of the Tweed, being chalce- 

 dony mingled with green earth, bitumen, &c. in 

 the form of moss, and other appearances. They 

 receive their name from Moca, in Arabia ; that is, 

 like many other substances, not from their native 

 site, but from the mart where they were sold, 

 being brought to Moca from Cambaya in Hin- 

 dostan, which also transmits beautiful carnelians 

 and chalcedonies*. There are probably rocks of 

 amygdalite in that vicinity. It would appear 

 however that this rock is among the rarest pro- 

 ducts of nature, having seemingly been observed 

 only in the four countries above mentioned ; Hin- 

 dostan, Sicily, Scotland, and the neighbourhood 

 of Ober stein. 



STRUCTURE II. AMYGDALITE WITH CALCAREOUS SPAR. 



Of this the toad-stone of Derbyshire affords Toad-stone, 

 a well-known example. Patrin mentions another 



* It is said that the fine carnelian is produced by art from no- 

 dules of a kind of chalcedonic flint, which are left in the heat of 

 horse-dung for many months. One of these flints I received from 

 my highly-respected friend Mr. Ferguson, whose noble collection of 

 minerals is known to all Europe. But, in the oriental phrase, his 

 lore of science, and generous spirit, surpass all the gems in his 

 cabinet. 



