504 



MINERALOGY. 



rtryctogno- frequently rest on each other, or intersect each other. 



v '? Externally shining and splendent ; internally shining 



"~ Y """ and pearly, inclining to vitreous. Fracture uneven. 

 Fragments rhomboidal, or indeterminate angular, and 

 rather sharp-edged. Is translucent, semi-transparent, 

 or transparent. Is rather sectile, and very easily fran- 

 gible. 



Chemical Character*. It melts before the blowpipe 

 into a white friable enamel, without very sensibly 

 tinging the flame : after a short exposure to heat it be- 

 comes opaque, and has then acquired a somewhat caus- 

 tic acrid flavour, very different from that of sulphuret- 

 ted hydrogen, which heavy-spar acquires in similar 

 circumstances. These characters apply also to the 

 other subspecies. 



Constituent Paris. 



Strontian and Sulphuric Acid . 97 601 

 Sulphate of Barytes . . . 00.975 



Silica 00.107 



Oxide of Iron, and intermixed Hy- 

 drate of Iron . . . 00.646 



Water 00.248 99.577 



Slromeyer, in Got. Gel. Anz. 1812, 22. 114. 

 Geognostic and Geographic Situations. Occurs in 

 trap-tuff in the Gallon Hill at Edinburgh*, and in red 

 sandstone at Inverness. Is frequent along with some 

 of the other subspecies at Aust Passage, and elsewhere 

 in the neighbourhood of Bristol, and in the islands in 

 the Bristol Channel, particularly in Barry Island, on 

 the coast of Glamorganshire; also in amygdaloid at 

 Bechely, in Glocestershire t ; and it has been found on 

 the banks of the Nidd, near Knaresborough, York- 

 shire. 



SECOND SUBSPECIES. 



Prismatic PRISMATIC CELESTINE, Jameson, Saulenformiger 

 celestinc. Zolestin, Werner. 



External Chaiacters. Colours white and blue. Oc- 

 curs massive, also in distinct concretions, which are 

 thick, straight, and wedge-shaped prismatic ; but most 

 frequently crystallized. The following are the most 

 frequent crystallizations: 1, Long oblique four-sided 

 prism, flatly bevelled on the extremities, the bevelling 

 planes set on the obtuse lateral edges. Sometimes the 

 angles between the bevelling and lateral planes are 

 more or less deeply truncated, and thus form a four- 

 planed acumination, in which the acuminating planes 

 are set on the lateral edge. 8. Sometimes the acute 

 edges of the preceding figure are truncated, and thus a 

 six-sided prism is formed. Crystals middle-sized, and 

 scopiformly aggregated, under an acute angle, and 

 forming druses. Externally smooth, splendent, and 

 resinous. Internally glistening and pearly, inclining 

 to resinous. Cleavage the same as in the foliated sub- 

 species. Fracture uneven. Fragments wedge-shaped 

 and indeterminate angular. Is translucent, or transpa- 

 rent. In other characters it agrees with the preceding 

 subspecies. 



Sicily. 



Constituent Parts. Strontian . . 54 



Sulphuric Acid . 46 100 

 Vauquelin. 



Geognofiic and Geographic Situations. It occurs in 

 drusy cavities in a bed of sulphur, which is associated 

 with gypsum and marl, in the valleys of Noto and Maz- 

 zara, in Sicily. 



THIRD SUBSPECIES. 



Oryctogno- 



S). 



FIBROUS CELESTINE, Jameson. Fasriger Zolestin, ,!"~~ v ~~"' 



Werner. J^".' "" 



External Characters. - Colours blue, grey, and 

 white. Occurs massive, also in distinct concretions, 

 which are straight, parallel, and sometimes curved, fi- 

 brous. Internally glistening and pearly. Cleavage 

 indistinct. Fragments splintery. Translucent In 

 other characters it agrees with the preceding spe- 

 cies. 



Conslit. Parts. Strontian . . 56.0 



Sulphuric Acid . 42.0 98.0 



Klaproth, Beit. b. ii. s. 97. 



Gf agnostic and Geographic Situations. Occurs in the 

 red sandstone formation near Bristol ; imbedded in 

 marl, which is probably connected with gypsum, at 

 Frankstown in Pennsylvania ; and at Bouveron, near 

 Toul, in the department of Meurthe in France. 



FOURTH SUBSPECIES. 



RADIATED CELESTINE, Jameson. Strahliger Zo'Ies- Radiated 

 tin, Werner. celestine. 



External Characters. Colour milk-white, which 

 rarely approaches to yellowish and snow white. Occurs 

 massive ; also in prismatic concretions, which are sco- 

 piform radiated, collected into others which are wedge- 

 shaped, and these again into very large and angulo- 

 granular concretions. Internally shining and splendent, 

 and lustre pearly, slightly inclining to vitreous. Frag- 

 ments wedge-shaped and splintery. Translucent or 

 s e mi transparent. In other characters agrees with the 

 other subspecies. 



FIFTH SUBSPECIES. 



FINE GRANULAR CELESTINE, Jameson. Fein Kb'r- Fine gra- 

 uiger Zolestin, Werner. nulw cele- 



External Characters. Colours greyish and yellow- tine. 

 ish-grey, and the first inclines sometimes to olive. 

 green. Occu*s massive, in fine granular concretions, 

 in spheroidal or reniform masses, which are often tra- 

 versed by fissures that divide its surface into quadran- 

 gular pieces, which are sometimes lined with minute 

 crystals of celestine. Towards the surface it has a 

 marly aspect. Internally dull and glimmering, and 

 pearly. Fracture fine splintery, passing into uneven. 

 Fragments blunt-edged. Opaque, or translucent on 

 the edges. In other characters it agrees with the pre. 

 ceding subspecies. 



Chemical Characters Sulphate of Strontian 01.42 



Carbonate of Lime 8 33 



Oxide of Iron . 0.25 



100.00 



Vauquelin, in Brogniart's Mineralagie, t. i. p. 258. 



Geognoslic and Geographic Situations Occurs im- 

 bedded in marly clay, with gypsum, at Mortmartre, 

 near Paris ; and is said to form a whole bed in Cham- 

 pagne. 



GENUS VI. LEAD-SPAR. 



One and three axes. Cleavage rhornboidal, pyrami- LEAD- 

 dal, prismatic. Hardness ranges from 2.5 to 4.0. If SPAB. 

 above 3.5 the specific gravity is equal to 6.5 and more. 

 Specific gravity ranges from 6.0 to 7-2. 



This genus contains five species, viz. 1 . Di-prismatic, 

 or white lead-spar. 2. Rhomboidal, or green and brown 



It was discovered in the Calton Hill by Mr. Sivright of Meggetland. 

 It was discovered in the Uechcley amygdaltid by Dt. Daubeny. 



