04 
A SYSTEM- OF ‘ 
Thefe are known by the following cha- 
rafters. 
1. Their texture and compofition confift of 
thin flexible particles, divifible into plates' 
or leaves, having a Ihining furface. 
2. Theie leaves, or fcales, expofed to the 
fire, lofe their flexibility, and become 
brittle, and then feparate mto thinner 
leaves : but in a quick and ftrong firev 
they curl or crumple, w^hich is a mark of 
fufion , though it is very difficult to reduce 
them into a pure glafs by themfelves, or 
without addition. 
3. They melt pretty eafily with borax, the 
microcofmic fait, and the alcaline fait j and 
may, by means of the blow-pipe, be 
brought to a clear glafs, with the two 
former falts. The martial mica is, how- 
ever, more fufible than the uncoloured 
ones. 
There is not yet difco^^^ered any loofe 
earth of this kind, but it is always found 
indurated. 
;S^EGT. XCIV. 
K Colourlefs or pure mica ; Daze, Glimmer, 
or Glift ; Mica alha^^ ft^e pur a, 
1. Of large parallel plates. Mica conftans 
lamellis magnis parallelis. Mufcovy glafs, 
• Vitnirn Mufcoviticum. 
Is tranfparent as glafs ^ found in Siberia^ 
and Elfdalen in the province of Wer-' 
melafid.' 
2. Of fmall plates. Mica /([uamofa^ from* Silf- 
verberget, at Runneby, in the province 
of Blekinge. 
3. Of 
