LIME. 



in combination with tTie planes of Hos. 2, 5, ly, 17, 23, 

 and wil'i remains of thj planes of tlie primitive rhomboid. 

 Ha^ been found in Hungary, and other places ; but does 

 not appear to occur in Enirland. 



39. PyramlLd doJ.'cah^dron of icp 58'. — The complete do- 

 decihedron occurs in Germany ; nearly complete, with planes 

 of Ml. t7 at the points of the pyramids, it is Haiiy's chaux 



42', and three under one of 112^44'. The complete do. 

 decahedron of thss modilicaticn is fcarce, but occurs in Der- 

 by(hire. In combination willi the planes of other modifica- 

 tions, particularly with Nos. 2 and 14; 2, 14, and 47; 2, 4, and 

 50, it is found in Derbyfliire and Cumberhmd ; and com- 

 bined \yith planes of feveral other rr:odii;cations, count 

 B jurnon has fecn it among the cryHals of calcareous fpar 



c^rh. fixilttodkhnih (p!..2J. fig. 22); with the fummit that accompany the filver ores of Potofi; one of thefe cr'\-f. 

 interceoted by N" 3, and with trapezoidal planes of No. 2, tals, the refult of eight moditications, has 66 planes 

 it cOTlH'.utes the fame crylhiiograplier's ciiaux carb. oc!ode- Haiiy's i haux carb. num!:riqui{\. des Min. No. 10 



chn^lt (ib. fig. 51.) ; its planes are a!fo feen in his chau)i 

 cjrb. zon.iire (pi. 26. fig. 39.) in combination with thofe 

 of N.) I, and of No. 17, which latter are the characteriltic 

 planes. Alfo the variety defcribed by Hsiiy under the 

 name oi qu'tntiforme, (Ann. da Muf. vol. ii.) has fmall planes 

 of this :?9;h modification, which has hitherto been found 

 principally in Ger.nany. 



40. Acute pyran'id^.l dodecahedron of 26^ 34'. — This dode- 

 cahedron is not unfrequently feen i;i its complete ftate, but 



06.) ap- 

 proaches very near this modiiicalion in the meafurement of 

 its angles. 



4j. Acute pyramidal dulecahedron of ^6' Jo'.— Mio-ht eafily 

 be miftaken for the dodecahedron. No. 36, in which, however,, 

 the cleavage takes place on the more obtufe edges. The do- 

 decahedron in its complete ftate ha.": been found in Derbviliire, 

 wliere this modification occurs in combination with the planes 

 of feveral others; the mo!f complic:ited among them is a 

 cryftal, produced by ten modifications, five of which belong 



its points, on account of their great fragility, are generally to rhomboids and four to dodecahedrons, which, together 

 broken. It occurs in Germany, from wiiich country, and with the planes of the prifra No. 2, form a cryllal of 84 

 from Derbyfhire and Cumberland, are alfj procured groups plane?, 

 of crvltals, including the plaaes of this modification, in com- 

 bination with others, fuch as Nos. i, 2, 3, 17, 19, 21, 22, 

 59, and 50. 



41. Acute pyramidal dodecahedron of 1 3 53'- — This is the 

 lail, and at the fame time the moit acute, of the feries of 

 pyramidal dodecahedrons produced by a decrement along the 

 edges of the bafe of the primitive rhomboid, and confe- 



46. Acute pyramidal dodecahedron of 40 2^'. — Refembles 

 the dodecahedron, No 45, with regard tothe inclination 

 of its planes to each other ; but it is much more acute.- 

 On the otiier hand it approaches near the dodecahedron, 

 No. j6, in the meafurement of the folid angle of its fum- 

 mit ; but in thi« the inclination of the planes is different,., 

 not to mention the difference in the cleavagfe. This dode- 



{j'lently with cleavage at the fummit on the more obtufe cahedron in its compL te ftate is very fcarce, it has, however 

 edges of the pyramid. This dodecahedron occurs complete, been found in Derby fti.ire and Cumberland ; the combinations 



of its planes with thofe of other modifications, fuch as 

 Nos. I, 2, 3, 4, 6, 17, id, and thofe of the primitive 

 rhomboid, are more frequently met with in thofe oarts of 

 England. 



47. Acute pyramtiLd dodecahedron of 45" 2'.— This appears- 

 to be peculiar to the fame places, in which the cryftals wi'th 

 the planes of the preceding modification are found. The 

 complete dodecahedron is feldom feen. It is moft frequently 

 found in combination with theprifm No. 2: the ano-Ics of three 

 alternate edges being very obtufe, its pyittmid appears al- 

 moR trian^'ular. Thefe cryllals are in general very tranf- 

 parent and beautiful. 



48. Acute py. amdal dodecahedron of 44" la'. — This is but 

 little more acute than the dodecahedron of the preceding 

 modification ; but the planes of the latter meet each other, 

 three under an angle of 163' 50', and three under one of 

 84^ ; while in this 48th modification the fame planes meet 

 three under 150° 8', and three under 97' 12'. The dode- 

 cahedron in its complete ftate has not yet been found. Its- 

 planes occur in cryftals from Cumberland and Derbylhire, 

 in combination with thofe of Nos. 2, 14, ^2, 36, and 4J. 



48*. Acute pyram-dal dodecahedron of ifV 3.1'. — The planes, 

 of this modification are thofe marlted x in the figures of 

 Haiiy's chaux carb. paradoxal (pi. 27. fig. 42.)^ delojiquf 

 (ib. fig. 46.), -a-cA contplexe (ib. fig. 43.) 



49. Acute pyramidal dodecahedron of ^g 9'. — The dodecahe- 

 dron of this modification in its compiote ftate is from Hun- 

 gary. Combined with the planes of (everal other modifica- 

 tions, it occurs principally in Derbyfnire; one of the cryl- 

 44. AcuJe dodecahedral pyramid of 61'^ 4"]'. — Thmigh the tals from thence, figured by count Bournon, is compofed of 

 olid angle of the fummit of this dodecahedron differs but 90 planes, being the refult of nine modifications. 



hut, on account of its great fragility, is generally feen in a 

 broken ftate ; fometimes two oppofite planes of the pyramid, 

 having increafed is fize, fo that they meet no longer in a 

 point, give rife to cuneiform pyramids. Nor is it uncom- 

 mon to fee four oppofite planes in the fame cafe. Such 

 cryftals bear great refemb'aace to certain varieties of arra- 

 gonite, from which they are, however, eafily diftinguifhed 

 by their much greater fragility, and by their lamellar 

 ftruclure. It has been obferved with veftiges of the primi- 

 tive planes, and in combination with thofe of feveral other 

 modi'u-ations : in one cryftal there are no lefs than 60 planes, 

 being the refult of feven different modifications. The cryftals 

 exhibiting planes of this modification are moftly found in 

 Cumberland, Derbyftiire, and on the Hartz. 



42. Acute pyramidal dodecahedron of 6-^^ ^y'. — With this 

 bf^gins the feries of thofe dodecahedrons which are the refult 

 of a decrement of the lamiris at the acute angles, on the 

 bafe of the primitive rhomboid. Hence the cleavage takes 

 place at the fummit on the lefs obtufe edges. Is found in its 

 complete ftate, and combine.! v/ith the planes of Nos. 36, 

 and 36 and 2, in Derbyihire ; but belongs to the more fcarce 

 raodilications of calcareous fpar. 



43. Acute dodecakedral pyramid of 63' 36^ — This has 

 been found in a complete ftate in Derbyfhire, where, as well 

 as in Cumberlaiid, it occurs alfo combined with the planes of 

 feveral other modifications, forming, in fome inftances, very 

 complicated cryftals, fuch as that of fig. 476 in the work 

 before us, the 102 planes of which are the refult of eleven 

 modifications. 



little from that of the preceding modification, yet there is a 

 great difference in the inclination of their planes ; in the pre- 

 ceding dodecahedron thefe meet each other under three angles 

 of I j8' 22', and three others of 96^ 40', while in this 44th 

 moiificatioa they meet three of them under an aiigis of 140'' 



90 planes, being ' 



JO. A.itte pyramidal dodecahedron of 2^" 25'. — To this pro- 

 bably belong the pyramidal planes of Haiiy's chaux carb, 

 acutangle. This modification has hitherto been principally 

 found on the Hartz, it occurs however alfo, combined witiu- 

 the planes of feveral others, in Derbyfhire apd otter parts 



