333 
formerly supposed to be Zeolite , &c. 
of square plates, which vary in thickness. The angles of the 
several square laminae, which are applied to each other are not 
always coincident. They are of a bright wax yellow. The 
sides of the largest of these square laminae is about a quarter 
of an inch. This last species is frequently found adhering to 
the sides of quartz crystals, in the cavities of granite. 
The other species of this mineral consists of an assemblage 
of crystals closely compacted together in the form of mam- 
millary protuberances, in general, of the size of small peas, 
intimately connected with each other. A stratum of these 
about -§■ of an inch thick is spread upon a layer of quartz, in 
the cavities or fissures of a species of compact granite. The 
striae of which these mamillae consist diverge from a centre, 
like zeolite. Some of the individual striae, in some cases, over- 
top their fellows, in these globular assemblages, and evidently 
assume, on their projecting points, a crystallized form. 
A. 
( x . ) The detached crystals of the former species are easily 
reduced to powder, of a brilliant whiteness. At the temperature 
56° of Fahrenheit, its specific gravity was found to be 2,22. 
(2.) The hardness of the more compact species is sufficient 
to scratch calcareous spar. At the temperature 55 0 , its specific 
gravity was 2,253. I* does not imbibe water. 
( 3. ) Some of the crystals exposed, on charcoal, to the flame 
of the blowpipe suddenly and strongly driven upon them, 
decrepitate : if they are gradually exposed to the flame they 
grow opaque, and become more light and tender : but they 
show no signs of fusion under the strongest heat. 
( 4. ) The phosphate of soda and ammonia takes up a piece 
