486 



MINERALOGY. 



Bastanes in Beam, all in France. America. It is found 

 in the trap-rocks in Kannioak in North Greenland, and 

 in the Haasen Island, also in North Greenland. Spe- 

 cimens of it have been met with at Guanaxuato in 

 Mexico, but not in Peru Asia. It occurs in the trap- 

 rocks of Van Diemen's Land, and in the neighbouring 

 islands. Africa. It is enumerated amongst the simple 

 minerals contained in the trap or lava rocks of the isle 

 of Bourbon. 



SECOND SUBSPECIES. 



Coralloidal 

 arragonite. 



CoRALLOIDAL AllHAOONITE. Jameson. 



External Characters. Its most frequent colours are 

 varieties of white. It occurs massive, reniform, tube- 

 rose, coralloidal, imperfect globular ; in distinct con- 

 cretions, which are fibrous, generally straight, seldom 

 curved, and stellular and scopiform ; sometimes also 

 in reniform curved lamellar, and large angulo-granular 

 concretions. Lustre glimmering, or glistening and 

 pearly. Fracture fine splintery. Fragments wedge- 

 shaped and splintery. Translucent, or translucent on 

 the edges. In other characters, agrees with the pre- 

 ceding subspecies. 



Geognostic and Geographic Situations. \t is found 

 in Dufton Fell in Cumberland, also in the iron mines 

 of Stiria and Carinthia, and at St. Marie aux Mines. 

 Limestone. II. LIMESTONE, Jameson Rhomboedrischer Kalk- 

 Haloide, Mohs. 



Rhomboid = 105 5'. The most perfect cleavages 

 are in the direction of the faces of the primitive rhom- 

 boid : less perfect in the direction of a flatter rhom- 

 boid ; a third still less perfect, which is parallel with the 

 planes of a six-sided prism ; and a fourth, the most 

 imperfect, which is parallel with the terminal planes 

 of the six-sided prism. Hardness = 3.5. Sp. gr. = 

 2.5, 2.8. 



This species is divided into twelve subspecies, viz. 

 1. Foliated Limestone ; 2. Compact Limestone ; 3. 

 Chalk ; 4>. Agaric Mineral ; 5. Fibrous Limestone ; 

 6. Calc-Tuff ; 7. Peastone; 8 Slate-Spar ; 9. Aphrite; 

 JO. Lucullite; 11. Marl; 12. Bituminous Marl Slate. 



FIRST SUBSPECIES. 



Foliated FOLIATED LIMESTONE, Jameson. Blattriger Kalk- 

 limestone. stein, Werner. 



This subspecies is divided into two kinds, viz. Cal- 

 careous-spar, and Foliated Granular Limestone. 

 First Kind. 



Calcareous- CALCAREOUS-SPAR, or CALC-SPAR, Jameson Kalk. 



spar- spath, Werner. 



External Characters. Its colours are white, grey, 

 red, blue, green, yellow, yellowish-brown, and grey- 

 ish-black. White and grey varieties occur more fre- 

 quently in the massive ; yellow, green, and red, in 

 those which are cry stall zed. White-coloured trans. 

 parent varieties are often iridescent. It occurs mas. 

 sive, disseminated, globular, botryoidal, reniform, tube- 

 rose, stalactitic, tubular, cellular, and curtain-shaped ; 

 also in distinct concretions, which are large coarse, 

 rarely small, angtilo-granular ; sometimes very thick, 

 thick and thin, prismatic, generally wedge-shaped pris- 

 matic; always straight; sometimes parallel, sometimes 

 scopiform prismatic ; and these are intersected by lamel- 

 lar concretions which are fortification-wise bent, and very 

 frequently crystallized. The suite of crystallizations 

 of calcareous-spar far exceeds in extent that of any 

 other mineral hitherto discovered*. The principal 



varieties are by Werner, according to his method, Oryctogns- 

 brought under three classes or subdivisions, which not > 

 only form series amongst themselves, but are connected ""^ "V* 1 "'' 

 together in such a manner, that the last member of the 

 third class joins with the first member of the first class, 

 and thus the whole forms a very beautiful returning 

 series. Each of these divisions have their characteris- 

 tic crystalline form, viz. The first an nctit? double, six- 

 sided pyramid; the second an equiangular iix-\idcd 

 prism, (including the six-sided table ;) and the third 

 a rhombuid or three-sided pyramid. 



I. Accute six-sided Pyramid- 



When perfect, it is always acute, and two and two 

 'ateral planes meet under obtuser anglts than the 

 others. It is generally obliquely streaked, but the 

 streaks run from the acute towards the obtuse edges. 

 It occurs, 



A. Single. 



B. Double. The lateral planes of the one, set obliquely 



on the lateral planes of the other, so that the edge 

 of the common base forms a zig-zag line. 

 These pyramids occur either perfect, or in the fol- 

 lowing varieties : 



1. The apex acuminated with three planes, which are 

 set on the obtuse lateral edges. These are parallel 

 with the cleavage. 



2. The apex flatly acuminated with three convex faces, 

 which are set on the acute lateral edges. The con- 

 vexity is in the direction of the axis of the double 

 pyramid. 



3. The angles on the common base of the double pyra- 

 mid truncated, thus forming a transition into the six- 

 sided prism. 



4. The acute lateral edges of the double pyramid some- 

 times truncated, and either with straight and smooth 

 planes, or with convex and uneven planes. 



5. Twin-crystal. 



The double six-sided pyramids apparently pushed into 



each other, in the direction of their length, in which 



they are either 



(I.) Unchanged in position, when the acute edges 

 rest on the obtuse edges ; or they are 



(2.) Turned around one-sixth of their periphery, so 

 that obtuse edges are set on obtuse edges, and acute 

 edges on acute edges ; and the alternate angles on 

 the common base have broken re-entering angles ; 

 or the angles on the common basis are truncated, 

 and thus a transition is formed into the next fol- 

 lowing principal form. 



II. Equiangular Six-sided Prism. 



It is equiangular, but generally with alternate broad 

 and narrow lateral planes. It originates from the pyra- 

 mid No. 3. ; and hence it presents the following varie- 

 ties: 



1. The equiangular six-sided prism, acutely acumi. 

 nated with six planes, of which two and two meet 

 under obtuse angles, and each is set obliquely on the 

 lateral edges. Sometimes the acute acuminating 

 edges are truncated, or they are bevelled, and the 

 edges which the bevelling planes make with the 

 broad lateral planes, truncated. 



In other varieties, the apices of the acuminations 

 are more or less deeply truncated, and sometimes so 

 deeply, that the acuminating planes appear as trun- 

 cating planes on the angles of the prism. 



* Rome de Lisle enumciatcs 26 varieties of calcareous-spar .HaUy above 150, and Bournon 6*2. Many more might be described. 



