MINERALOGY. 



481 



Oryetogno- 

 7- 



Scaly foli- 

 ated gyp- 

 lum. 



Earthy 



Vf 'ntriMr. 

 trilk 



Prlttnatk 

 gypmm. 



SjHIITT 



uibjruntr. 



FIFTH SCBSPECIES. 



SCALY FOLIATED GYPSUM, Jamttoti. Schaumgvps, 

 n enter. 



External Character!. Colours yellowish-white and 

 mow-white. Occurs massive and disseminated ; also 

 in distinct concretions, which are small and scaly gra- 

 nular. Internally glistening and pearly. Fracture 

 small scaly foliated. Fragment* indeterminate angular, 

 and blunt-edged. Opaque, or translucent on the edges. 

 Sectile, and easily frangible. 



ficagnijitic and Geographic Situations It occurs 

 with selenite and compact gypsum at Montmartre, near 

 Paris, in that formation of gypsum named by Werner 

 the third or yellow flcetz gypsum formation. 



SIXTH SUBSPECIES. 



EARTHY GYPSUM, Jameion. Gyps-crde, Werner. 



External Ckiracler$. Colour yellowish- white, which 

 passes into yellowish-grey, and sometimes inclines to 

 now. white. Composed of fine scaly or dusty part 

 which are more or less cohering. Feebly glimmering. 

 Feels meagre, and rather fine. Soils slightly. Light. 



Geognostic Situation. It is found immediately un- 

 der the soil, in beds several feet thick, resting on gyp- 

 sum. and also in neU or coteniporaneous masfra im- 

 bedded ii. 



Geographic Situation It is found in Saxony, Swit- 

 zerland, Salzburg, and Norway. 



MONTMARTRITE. Chaux Julphat.'-e calcarifcre, 



ucTt 4- Haui/. Gvpsum of Montmartre. 



Ef'ernal Char-ilert. Colour yellowish. Occurs 

 ivp, but never crystallized. Soil. Effervesces 

 with nitric acid. 



The Montm irtrite is composed of gypsum and car- 

 bonate of lime. This carbonate is converted into 

 quicklime in the furnace, and thus a kind of mortar is 

 formed : it is on this account, that the plotter made of 

 thi-t mineral may be used in work exposed to the wea- 

 ther ; while that of pure gypsum, on exposure, soon 

 yields to the action of rain. The raontmartrite con- 

 tains, about Sulphate of Lime, 8.8 



Carbonate of Lime, 1 7 100 



II. PRISMATIC GYPSUM, or ANHYDRITE, Jameion. 

 Priimatisches Gyps Haloide, Moh'. Muriacit, Werner. 



Prism = 10O. 8'. Three cleavages, perpendicular to 

 each other. Hardness=3 0. 35. Specific eravitv = 

 2.7-3.0. 



It is divided into five ubpeciw, viz. Sparry Anhy- 

 drite. Scaly Anhydrite, Fibrous Anhydrite, Con- 

 chuidal Anhydrite, Compact Anhydrite. Vulpinite. 

 r:UnKrifJ 



Clauberite. 



FIRST SUBSPECIES. 



SPARRY ANHYDRITE, or Ct bE-Spin, 'Jameson. 

 WurfeJjpath, Wtincr. 



External Character!. Chief colour white, which 

 pastes 00 the one side into blue, ami on the other into 

 red. Occurs massive ; alco in distinct COIICTI-: 

 which are thin and straight lamellar, collected into 

 others which are large granular. Sometimes crystal- 

 lized in the following figures. 



1. Rectangular four-sided prism : it is sometime* so 

 low as to appear as a four-sided table. 2. Broad six- 

 Sided prism. 3. Eight-sided prism. 4. Broad reel- 

 anguW four-sided prism, acuminated on the extremi- 

 ties with four planes which are set on the lateral edgei, 

 and the apex of die acumination deeply truncated. 



OU XIT. PART. Ik 



Externally shining or splendent, and pearly : inter- Oryetogno- 

 nally splendent and pearly. Fragments cubical. Frac- '*' 

 ture conchoidal. Alternates from transparent to strong- > "V 1 

 ly translucent, and refracts double. Brittle, and very 

 easily frangible. 



Chemical Characters. When exposed to the blow, 

 pipe, it does not exfoliate, and melt like gypsum, but 

 becomes glazed over with a white friable enamel. 



From Bern. From Tyrol. 



Conttit. Parts. Lime, 40 41,75 



Sulphuric Acid, 60 55.00 



Muriate of Soda, 1.00 



100 97-75 



Hauy, Traite, t. iv. Klaprolh, Beit 

 p. 349. b. iv. s. 235. 



Go-gnostic and Geographic Situations. It is some- 

 times met with in the gypsum of Nottinghamshire. 

 In the salt-mines of Halt in the Tyrol, and in other 

 countries. 



SECOND SUBSPECIES. 



SCALY ANHYDRITE, Jameion. Anhydrite, Werner. Scaly an- 

 External Character*. Colours white, smalt-blue, and *"*"" 

 rarely grey. Occurs massive, and in small granular 

 concretions. Lustre splendent and pearly. Cleavage 

 imperfect and curved. Fragments not particularly 

 blunt-edged. Translucent on the edges. Easily fran- 

 gible. 



Constituent Parts. Lime, 41.75 



Sulphuric Acid, 55.00 

 Muriate of Sod.i, 1.00 97.7.5 

 Klnprulh, Ik-it, b. iv. s. 235. 



GeogHotlic and Gropraptiic Situations. It is found 

 in the galt-mmes of Hall in the Tyrol, 5088 feet above 

 the level of the sea. 



THIRD SUBSPECIES. 



FIBROUS ANHYDRITE, Jameson. Fasriger Muriacit, 

 Werner. 



External Characters. Colours red ; also blue and Fibroin an. 

 grey. Occurs massive, and in coarse fibrous concre- hydritc. 

 lions which are straight or curved, and sometimes 

 stellular. Internally glimmering and glistening, and 

 pearly. Fragments long splintery. Translucent on 

 the edges, or feebly translucent. Rather easily {'ran- 

 gible. 



Geographic Situation. It is found in the salt-mines 

 nf Berchtesgaden, and at Ischel in Upper Austria, at 

 Hall in the Tyrol, Salz on the Neckar, Carinthia, and 

 Tiede near Brunswick. 



Uies.1'he blue varieties are sometimes cut and po- 

 li-hed for ornamental purposes. 



FOURTH SUBSPECIES. 

 CONVOLUTED ANHYDRITE, Jameson Gekrostein, Convoluted 



Werner. anhydrite. 



External Characters. Colour dark milk-white. Oc- 

 curs massive; also in distinct concretions, which are 

 thick lamellar, and intestinnlly convoluted or contort- 

 ed, and these are again composed of Bothers which are 

 thin prismatic. Internally j;!i:-ti-ning or glimmering, 

 and the lustre pearly. Fracture small and fne splin- 

 tery. Fragments indeterminate angular, and rather 

 sharp-edged. Translucent on the edges, or translucent. 

 Constituent Paris. Lime, 4.' 



I, 5&.50 



Muriute "I Soda, 0.25 98.75 

 Klaprolh, Eeit. b. iv. s. SS3. 

 SP 



