MINERALOGY. 



501 



GKITOS V. BARYTE. 



One and three axes. Cleavage rhomboidal and pris- 

 matic. If cleavage rhomboidal, specific gravity = 4.2 

 and more. Hardness = 3.0, 3.5. Sp. gravity=3.6 

 4.6. 



I. Di-Pa-sMATic BARVTE. or STRONTIANITE, Jane- 

 tmi. Dinrismatischer Ha)-B*ryt, Mohi. Strontian, 

 H'crner. 



Vertical prism = 117* 19*. Horizontal prism in the 

 direction of the sma'lcr diagonal. Cleavage in the 

 d rection of thep'anefc nt both prisms. Hardness = 3.5. 

 Sp gravity = ''.C 3.8. 



External Character*. Colour pale asparagus-green, 

 which sometimes incline- to apple.green, sometimes to 

 yellowish- white and greenish-grey. The greenish- 

 grey variety sometimes passes into milk and yellowish 

 white, and pale straw yellow. Occur* massive, in dig. 

 tinct concretion*, which are sconifnrm, radiated and fi- 

 brin* and crystallized. The primitive form is an 

 oblique ti ur->ided prism bevelled on the extremities. 

 Its secondary figures are the following: 1. Acicularsix- 

 tid(-d prism. acutel> acuminated with six planes, which 

 re set on the lateral plafes. 4 Acicular acute double 

 six-sided pyramid. CrysuU are MMnetimes ocopiformly 

 nd manipularlr atrgreirated. Lu-tre of the distinct 

 concretion' nhininsj or glistening ; the fracture glisten- 

 ing, and pearly Fr.vtur< fine grained uneven. Frag- 

 ment* wedge shaped or plmtery. More or less trans- 

 lucent, ami -onu'timr* semi-transparent. Brittle and 

 ewihr fnn 



( lirm 01' I ' nrnctert. 1 fusible before the blowpipe, 

 but become* whitr and opaque, and tinges the flame 

 of ilaric purpl.- colour. Is soluble, with effervescence, 

 in muriatic or nitric acid ; and paper dipped in th so- 

 lution* thus produced, burns with a puiple flame. 



C^ntlilotnt Parti. Strontian. 61. XI 



Carbonic Acid, :: 

 Water, 8.50100.00 



Honr, F.din. Trans, lor 1790. 



Grr>/f*o<tic and Cirnfraphic Simaliont It occurs at 

 Strnnti.in in Argy'e-liire, in vein* that traverse gneiss, 

 long with galena or lead-glance, heavy-spar, and cal- 

 careou*-par 



2. RHOMBOIDAL BAHYTE, or WITIIERITF, Jameton. 

 RhomIx-dri-<-!i<r Hal-Baryt, M<,fix. Witherit, V.'rrnrr. 



Rhomboid^! 4 i4'. The most distinct cleavage is 

 that j)..r.lirl with the plane* of the rhomt>oid and ano- 

 ther les distiiu t parallel with the alternate planes of 

 the six aided pyramid. Hardne*s=3.0, S.3. Sp. jrr. 

 = 4*. 44. 



External Ckaracteri Colours white, grey, and yel- 

 Occur* maMJve, dii> initiated. in cru<4s, cellular, 



low. 



corroded, large globular, renilorm butrxiiidnl, nuUcti- 

 tic; alo in d.-tinrt concretions, which are wedge- 

 shaped, sometime* scopifonn radiated, and occasionally 

 MM into course granular. on- rarely crystallized. 



The following are tlie secondary form* : 



1. Equiangular six sided prism. 



a. Truncated on the terminal edges. 

 6. Acutely acuminated on the extremities with six 

 planet, which we set on the lateral plane* 



2. Acute double six-sided pyramid in which the la- 

 teral plane* of the one are' ft on the lateral planes 

 ot the other. 



The crystals are (mall, and very small, reldom middle 

 sized The prisms are uorm-tim. -copifonnl v grouped, 

 or they are in dru-es. Externally glistening ; inter- 

 nally shining on the cleavage, and glistening on the 

 fracture, and the lurtre i resinous. Principal fracture 

 ven, inclining to splintery. Fragment* wedge. 



shaped, or indeterminate angular. Translucent, rarely Oryctogn*. 

 semi-transparent. Brittle, and easily frangible. S J- 



Ckemieai Characters. Before the blowpipe it decre- ''Y^*' 

 pitates slightly, and melts readily into a white enamel; 

 it is soluble with effervescence, in diluted muriatic or 

 nitric acid. 



Coiutit. Partt. Carbonate of Barytes 96.3 

 Carbonate of Strontian 1 1 

 Sulphate of Uaryteg, 0.9 



Silex . 0.5 



Alumina, and Oxide of 



Iron . 6.2599.05 



Aikin, Geol. **>. v. iv pait ii, p. 442. 

 Gfofottic and Gtoumpfiic Silnatiom. lt occurs in 

 Cumberland and Durham, in lead veins that traverse a 

 secondary limestone, which rests on red sandstone, and 

 in tlnsi- it i.s associated with conillo <l,il arnigonite, 

 brown spar, earthy fluor spar, heavy spar, and galena 

 or lead-glance, white lead spar, green lead spar, copper- 

 pyrites, blue copper, malachite, iron-pyrites, sp-my 

 iron, calamine and blende. 



Uve* it is a very active poison, and in some dis- 

 tricts, as in Cumberland, it is employed I' r the purpose 

 of destroying rb. When dissolved by muriatic acid, 

 the solution thus obtained, is said to prove serviceable 

 in scroful i. 



3. PHISMATIC BARYTE, or HEAVY SPAR. Jameton. 

 Prisniatischcr Hal Baryt, Mob. Sdmerspath, Werner. * 



Pri*m=K)l e 5-^' The most distinct cleavaye is that 

 parallel with the terminal planes of the oblique tbur- 

 sided prism ; IMS perfect are those parallel with the 

 lateral rl.ine^ of the prisin. U:irdnr>.s J.O, 3.5 Sp. 

 gravity =4. 1, 46. 



Thii species is divided into nine subspecies, viz. 1. 

 Earthy Heavy spar, 2. Compact Heavy spar, 3. Granu- 

 Ur Heavy par, 4. Curved Lamellar Heavy spar, 5. 

 Straight Lamellar Heavy spar, 6. Fibrous Heavy spar, 

 7. Radiated Heavy spar, 8. Columnar Heavy spar, and, 

 9- Prism:U'C Heavy *par. 



FIRST fcuaspecir.s. 



EARTHY IIE.VVY SPAU, Jantf.ivn. Schwcrspath Erde, Enrthy 

 Werner. heavy sptr. 



External Characters Colours yellowish and reddish 

 white. Of friable consistence, and consists of feebly 

 glimmering, nearly dull, particle*, which are interme- 

 diate between scaly and dusty, soil fcvhly. and are 

 generally loose, or but feebly cohering. Feels meagre, 

 and rather rough. Specific gravity, 4.0. 



Ciimiitufit Partt it i* sulphate of Barytes. 



G'Opnoitic and Gengrui>liic Siluntiont. it occurs in 

 drusy cavities in veins of Ix'nvy >p,ir, in St.iffnrdsliire 

 nnd Derbyshire ; at Freylierg in Saxony ; Rieglesdorf 

 in Hessia ; and Mies in Bohemia. 



SECOND Si BSPECIEB 



COMPACT HEAVY SPAR, Jameton. Dicbter Schwer- 

 .path, Winer htiv > 



External Character* Colours white and grey. Oc- 

 cur* mnxsive, disseminated, reniform, semi-globular, 

 tuberose, with cubic impressions ; and in curved .a- 

 mellar concretions, internally glimmering Fracture 

 intermediate between coarse earthy, and fine-grained 

 uneven, which sometimes pastes into imperfect foliated, 

 and more rarely into splintery. Fragment- indetermi- 

 nate angular, and blunt-edged. Opaque, or translucent 

 on the edges. Rather ttectile, and easily frangible. Sp. 

 gravity, 4.84. 



(ieiignmlic and Geographic Situations. It is found in 

 the mines of Staffordshire and Derbyshire, where it is 

 named Cauk. 



