MINERALOGY. 119 



SECT. CX. 



Sparry Zeolites, Zeolites f-p at fits. 

 This refembles a calcareous fpar, though it 

 is of a more irregular figure, and is more 

 brittle. 



c. Light red, or orange-coloured, from Nya 

 KrongrufVan, one of the gold-mines at 

 Adelfors, in the province of Smoland. 



ever, for ihefe experiments none but the pureft pieces have 

 been picked, fuch as have been examined through a magni- 

 fying glafs, and been judged as free from heterogeneous 

 mixtures as poliible. It is to be wifhed, that thofe who have 

 a fuiheient quantity cf this ftone would continue thefe expe- 

 riments, in crder to difcover what fubftance it is that makes 

 this blue colour, which is (o conftant in the fire, fince it can- 

 riot depend either on copper or iron ; for though thofe metals, 

 cr. certain cccafions, give a blue colour, yet they never pro- 

 duce any other but what initantly vanifhes in the fire, and is 

 deftroved by means of an alcaii. What is mentioned in fe- 

 veral boo'<s about the preparation of the ultramarine from 

 1. 'v.r, can r>y no means be objected here, fince in thofe pro- 

 cefiss the filjrer employed is mixed with copper, and other 

 fubftances, which contain a volatile alcaii, whereby the blue 

 colour is produced + . 



In regard to the above-mentioned qualities of this ftone, it 

 cannot beclafTed under any other k.nd or earth than this. 



I Mr. Margraf baa fio r e, in his Ch*mt>:al Difiertntions, printed in 

 German in the year i;6r, pubiiihed forue experiments on the lapis lazuli j 

 and :n tlje chief agrees m in cur author, without, however, knowing any 



sgof thefe hii ttpeatAer<ti, Mr. Margraf alfo proves that there is no 

 c . pa ifl th s ftone ; and befides t'lls us, that he has found both a cal~ 

 carcom and a gypfec-us fubftance in v , although he took care to pick out 

 only the very pure bits &,r his experiments However, I am led to imagine, 

 that the calcareous fobftar.ee is net eflen ial to the txiftence of the lapis 

 lazuli, fince Mr. Cror.ftect exprefly fays, that the (lone he. tried c^id not 

 ferment at all with acids. He farther mentions this remarkable circum- 

 ftance, which makes it ftill more evident that the lapis Itzuii hf longs to 

 the* zeolites, \'.z. that, *hen calcined and diffolved in th? aciris of vitriol, 

 cf common lair, a--d of n'tre, it turned all thofe acids into a jelly. 

 However, he does not tafcc ?ny no'ice of its containing any filter, becaufe he 

 d'd oof profecute his experiments fo far on that point; but feme of his 

 experiments, Detertbeleft, fce.n to indicate, as if ali forts of lapis lazuli did 

 not con.ain filvcr, E. 



I 4 SECT. 



