GYPSUM: 
infinuates itfelf, by its prominent angle, into the re-entering 
angle of the one meae sent under it. Many of thefe len- 
ticular a are found in great variety at Mont- 
martre. 
All the ey ttlle of this fubftance have a remarkable ten- 
dency to altering their figure by exfoliation. Some will 
fplit into diverging lamin to a certain extent only: they 
are comp to, om alfo go by the name of, Lions’ paws, 
in fome parts of nd. For the i 
a which choke cryttals undergo, by their a 
affume a rounded form, fee Hatiy’s Traité, vol. ii 
rs S7ae: sed: 
The rhomboidal, tolunitiar, and acicular cry {tals are. _ 
quently feen grouped together in various manners, fometi 
oon each other in all raph ee alfo in fafcieular aun 
ftellular aggregations, and in drufes. Sometimes fmall 
pe Soo are ores in, and traverfe larger crytftals. 
ir fize, the belies vary from exceed- 
ng ree (at snty Teno, but alfo perfect cryftals have 
of above a foot in length, but they are cages) 
ay {mall. 
The trapezoidal planes of the cryftals are generally longi- 
tudinally ftriated, owing to the direétion of the lamme, the 
wo ot 
fracture is generally ftraiyht, fom ed ; 
this is the perfe&t cleavage, which is eafily o : but 
_ there are two others: lefs perfect ones, Seid oO the 
for uce the: Srp folids already mentioned as 
mer, p 
reprefenting the — 
When maffive it generally ‘prefents itfelf in large, and 
coarfe grained, sad ometimes - es Sag él 
form and columnar diftin 
It is — completly seine very foft and mild, 
flexible in a se, when divided into thin plates, 
; Prt “rmein, the e preferving | the curvature > given 
y heavy, its tec gravity — ftated as 2. a a 
ivan as 2.322 by M 
; einwas henbroeck, but only as 1.761 
(that arrears en 
rh of beniby gypfum, acgording to 
Bergmann, are 
Lime act 93000 
Sulphuric aca - — 
Water - - 2.00 
100 100 Bergm, Opuf. voli pe 135. 
riers capt are in — ares of the onal econ of 
mountains at a 
a ‘Mufkau, — Wehrau ; Bo hemia; particularly in 
Leutmeritz and Saatz circles 5 Upper in Neto Iichel, 
Vina, Sess uae: 
seen toll, 3 — chee aes 
as in veins, copper 
and lead: at ‘Herrengrund, a acar Neufohl, it occurs.in veins 
= 2 
perfectly fmooth : they are generally more 
Internally the f a ae gypfum is fpecular-fplendent. Its / 
imes ee — d 
y thick cunei- - fr 
feparates the valley of 
_this mountain is He: b 
oper. for the purpofe of working 
Dickes, sg 
imation: &e., ~esrinct in. Suoe Lufatia, 
the ous 
are often, tyne ome Liveenaiesistins 
ae 
func wah gh at of lee ie grain f 
of copper pyrites, and Tsrey coppér org, and near Tetfcheay 
Bohemia, in veins of galena. It has alfo been found with i 
native gold, and, by Patrin, in the Smenoviky filver mi 
the Altaic mountains, where it occurs in fchiftus. Nor i sit 
unfrequently feen in the form of hove acicular cryftals, 
in old neglected — en old 
fubftance of very recent Seeulidens: 
it occurs in Bova. Aaar cryftals, on native fulphur, andis ge. 
nerally met with in abundance near depofiiions of rock-falt, 
fuch as in thofe of Saltzburg and Upper Auttria 
mixed with clay it or exhibits the Jule 
called Pibesant; to this variety the name of Schi 
has been given by miners im Germa “When intimately 
mixed with flink-ltone it has a fapkt-brey colour, and on be- 
ing rubbed emits the — odour of that fubitance. 
eognoftic Relation of Gypfum in ele pgaresce <x: 
um 
& 
RE 
been doubted by fome oe pa 
apc to Mont Rofe,. — 
almoft exclutively to-the seo ion of micaceous  fhiftus 
Here this primitive rock frequently includes ftrata of pri 
mitive lime-itone, ferpentine, chlorite, ma netic iron, &c.: 
fometimes it pafles into argillaceous ‘fhiltus, but oftener 
into gneifs and granite. About 15,000. metres fouthward 
om the town Aoite, and ealtward from Cogne, @ 
mountain is feen, which conititutes part of the chain: that 
ogne fom that part o of Fenes; 
elevated 
y edge, 
more than 2100 feet above the Ga of the valley, and con 
part of the fummit e ths mows 
There it is vifible onl 
‘about twenty-three feet, its thicknefs be 
a 
ree feet > all the reit of its extent is hidden: ee a = 
‘mafies of rock, that, being) 
from the fummit, have covered the fides of the-mountz , fo 
that nothing pofitive can be faid refpecting its extent 
length and thicknefs, nor refpeCiing the circumftances of i 
fuper-pofition ; Daubuiffon has, however, feen traces of it at 
more than 150 feet diftance is laid 
cannot be conliderable, for at the pl 
ir a kind of roof, beneath which the wor 
ae eS set 
primitive gypfum- is of # beautiful -white ¢ 
