(ECONOMY 
5 * 
fand, the more eafily it concretes. But if an 
alcaline clay chances to be mixed with the 
fand, the freefione is generated more readily, 
as in the freefione called cos friatilis , particulis 
argillo-glarenfis , S. N. i. i. 
The flint i S. N. 3. 1. is almoft the only kind 
of ftone, certainly the moil common in chalky 
mountains. It feems therefore to be produced 
from chalk. Whether it can be reduced again 
to chalky i leave to others to inquire. 
Stalactites , S. N. 33. 1. or dr op-ft one is com- 
pofed of calcareous particles, adhering to a dry 
and generally a vegetable body. 
The incruftations S. N. 32. 5, 6, 7, 8. are 
often generated, where a vitriolic water con- 
nects claiey and earthy particles together. 
Slate by the vegetables, that are often in- 
clofed in it, feems to take its origin from a 
marfhy mould. 
Metals vary according to the nature of the 
matrix, to which they adhere, e. g. the py- 
rites cupri Fahlunenjis contains frequently ful- 
phur , arfenic , iron, copper , a little gold , vitriol , 
alum, fometimes lead ore , filver and zinck. Thus 
gold, copper , iron , zinck , arfenic , pyrites , vitriol 
come out of the fame vein. That very rich 
ore at Normark in Vermel andia, where 
4 it 
