HYDROUS SILICATES—GENERAL SECTION. 295 
Diff. The pearly basal cleayage and the forms of its glassy 
erystals at once distinguish it from the preceding species. 
The prisms are sometimes almost cubes, with the angles 
eut off by the planes of the pyramid ; but the difference in 
the lustre of the prismatic and basal faces ‘shows that it 
is dimetric. 
The name alludes to its exfoliation before the blowpipe. 
Obs. Found in amygdaloidal trap and basalt. 
Occurs in fine cr ystallizations at Peter’s Point and Par- 
tridge Island, Nova Scotia, at Bergen HL AN: J. ae Cliff 
Mine, Lake Superior region. 
Catapletite. A hydrous zirconium and sodium silicate, from Nor- 
way 
Dicitase and Chrysocolia. Uydrous copper silicates. See p. 141. 
Picrosmine, Pyrallolite, Picrophyll, Traversellite, Pitkarandite, Stra- 
konitzite, Monradite, are names of varieties of pyroxene in different 
stages of alteration. Xylotine is probably altered asbestus. 
Prehuite. 
Trimetric. JAZT=99° 56’. Cleavage basal. Sometimes 
In six-sided prisms, rounded so as to be barrel-shaped, and 
compo ed of a series of united plates ; also in thin rhom- 
bic or hexagonal plates. Usually reniform and botryoidal, 
with acr ystalline surface ; texture compact. 
Color light green to colorless. Lustre vitreous, except 
the face 0, which is somewhat pean: Subtransparent to 
translucent. H.=6-6:5. G, =2:8~2°96. 
Composition. H,Ca,Al0, Si,=Silea 43°6, alumina 24:9, 
lime 27-1, water 4: 4—100. B.B. fuses very easily to an en- 
amel- nice glass. Decomposed by hy drochloric acid, leaving 
a residue of silica in hght flakes, but the solution ‘does not 
gelatinize.. Yields a little water when heated in a closed 
tube. 
Diff. Distinguished from beryl, green quartz, and chal- 
cedony by fusing before the blowpipe, and from the zeolites 
by its superior hardness. 
Obs. Found in the cavities of trap. eneiss, and granite. 
Occurs in the trap rocks of the Connecticut Valley, and 
at Paterson and Bergen Hill, N. J. ; in gneiss at Bellows 
Falls, Vt.; in syenyte at Charlestown, Mass. ; and very 
abundant, forming large veins, in the Copper region of Lake 
Superior, three miles south of Cat Harbor, and elsewhere. 
The Fassa Valley in the Tyrol, St. Christophe in Dau- 
