MINERALOGY, U9 
any of it. Befides this, there are alfo fome 
fibrous particles in it, and fomethi’ng that 
refenribles a calcareous fpar : This however 
does not ferment with acids, but melts as 
eafy as the ftone itfelf, which becomes a 
black folid glafs in the fire. By calcina- 
tion it becomes red, and yields in aiTays 12 
or more per cent, of iron. No other fort of 
ore is to be found in it, unlefs now and 
then fomewhat merely fuperficial lies in its 
fiffures •, for this fcone is commonly, even to 
a great depth in the rock, cracked in acute 
angles, or in form of large rhomboidal dice. 
It is employed at the glafs-houfes, and added 
to the compofition of which bottles are 
made. By the Germans it is called Schwach 
or Schwartsjiein'^ at the Swedifh glafs-v/orks, 
^rappJIHol^ "Tegeljkiol^ ov Swartjkiol and at 
Jarhberg in Norway, Blah eft. In the air 
It decays a little, leaving a pow-der of a 
brown colour *, it cracks commonly in the 
fire, and becomes reddifli brown if made 
red hot. It is found 
1. Of coarfe pharfy particles, Particulis ma- 
jor ihus acerofis: 
a. Dark grey, from the top of Kinne- 
kulle in the province of YvTfiergott- 
land. 
h. Black, from Stallberget at Cilerfilf- 
verberget in the province of D alar ne. 
2. Coarfe- grained, Particulis majoribus gra- 
niilatis. 
a. Dark grey, from the uppermofi: fira- 
tum at Hunneberg in Wefcergottland. 
h. Reddiih, from Bragnas in Norway. 
c. Deep brown, from Gello in Norway. 
3. Of 
