mineralogy* 
121 
of them, when more nicely examined, may per- 
haps be found to belong to the fame order, and 
perhaps be fome kind of earth, whofe properties 
have been long and perfedlly known. 
The terra porcellanea Lunehurgica^ which Bruck- 
man rnentions, and Mr. Wallerius has ranked 
among the gypfa, may, perhaps, belong to this 
order : but I have not been able to procure a fpe- 
cimen of it, to compare it with the zeolites, 
which alfo is very fcarce, not being found in our 
country except in very fmall veins and cavities. 
To this fcarcity is owing, that it has not yet been 
tried in the fire together with other kinds, except 
with the fparry fluor. With that it does not fufe 
very readily, becaufe, when equal parts of them 
are melted together, an opaque flag or glafs is 
produced of the fame colour with the alcali of 
nitre, of a fibrous texture, and of an uneven fur- 
face. ’ 
Th^ quality of fweliing in the fire, like the 
borax, is peculiar to the criftals, (Se(5l. cxi.) be- 
caufe the other varieties rife only into fotne fmall 
blifters, which are of a white colour at their 
edges, and inftantly cover themfclves with a white 
glafly fkin, after which they become quite refrac- 
tory. 
SECT. CXIIL 
-The Ninth Order.. 
The Manganefe Kind, Magnefitc. 
The ftones belonging to this order, are in 
Swedifh called Brunftetiy in I^atin Syderea^ 
pr Magnefi(£ ntgr^^ in order to diftinguifh 
them from the Magnefia alba officinalis^ and 
in French Mangonefe^ &c. They are by fome 
litho- 
