MINER A-LO GY/ ■ yt: 
Langbanfhyttan in the province of Wer- 
meiand, and at Sponwik in Norway, 
r. Yellow, from Bohemia. 
This iaft mentioned, when calcined, 
is attraded by the load-ftone, andbeing^ 
allayed, yields 12 to 15 per cent, oi 
iron. 
* Jafper, when frefh broke, fo nearly refembles a bole of 
the fame colour, that it can only be dihinguiflied by its 
hardnefs. In the parilh of Orfa, in the province of Dalarne, 
there is a red bole found in fpaces like glands or kernels, in 
that fort of fandllone from which grindftones are cut ; and 
fome miles diftant, in the rocks at Serna, a red jafper of the 
fame colour and textuie as the above bole, is found in a 
much harder kind of fandftone. In other places jafper is 
found in fuch unfluous clefts, as if they had contained unc- 
tuous clays ; as pipe clays, and red chalk ; and there are 
likewife fome jafpers which imbibe water. May it not then 
be fuppofed with fome probability, that jafper is an indu- 
rated bole, a reddle, or terre verte ? That jafper, as well as 
thefe, conlifts of clay and iron ; though, by reafon of its 
being hardened, it becomes as dihiculc to extra6l thefe prin- 
ciples from it, as to reduce a fmall quantity of fcorified iron 
to its metallic form, when melted with a large quantity of 
flag or glafs ? That the fame bole or clay, together with 
another fubftance, perhaps lime, after being diflblved by a 
menflruum, not yet determined, is fufficient for the produc- 
tion of flint ftone ? and that fo much of the bole as was 
fuperfluous, being feparated from the mafs, is found ad- 
hering to the furface, or in the fifrures,&c. 
Thus one might imagine, that jafper could eafily be pro- 
duced, and that the foft kinds might become harder by 
length of time ; but its particles cannot be fuppofed to ap- 
proach nearer and nearer to one another during the harden- 
ing ; nor can it be imagined, that the jafper fliould by that 
means become of a finer texture. On the other hand, we 
know extremely well, and have the experience of it every 
where, that porphyry in the rocks decays into a white crufl, 
wherever it is expofed to the air, although internally it re- 
mains very hard and black ; for inflance, at Klitten, in Elf- 
dalen, in Sweden. From whence it may be fuppofed, that 
water, which waOies off the mouldered particles, muft by 
degrees collet them fomewhere, and at length prefent us 
F 4 with 
