I 



r 



f 



Fourth Sappleineiit to Daiias Mineralogy. 123 



prism of 1 20°], and hence questions whether the form is not hexagonal. Examined 

 optically it gave a simple black cross. — Grailich gives for the angle between the op- 

 tical axes in a Vesuvian mica of a pistachio and clear green color. 1°: brownish- 

 green, 2° ; bluish, 3°; greenish-black lu pumice, 4^ (Krystallug., p. 284). 



The composition by Kjorulf's analysis of green Vesuvian crystals, is (J. f. pr. 

 Ch., Ixv, IQO): 



Si 3tl ¥e ^g JS'a S ign. 



44-6S 19-04 4-92 20*89 2-05 6'9T 0'17=98-67 



Specimen probably impure from mixture with augite. Other Vesuvian micas have 

 afforded the composition of biotito, and this may be similar. 



A biotit€y one of the constituents of a rock from the Vosges called Minette (con- 

 sisting of biotite and orthocla^e, disseminated in a feldspathic base, and containing 

 also hornblende, and occurring in dykes intersecting even the Devonian), has been 

 analyzed by M. Delesse, who obtained (Ulnstitut, No. 1216, April, 1857): 



Si 51 Ma Pe fe Ca % K Na ti F fi 



41-20 12-37 1-67 6 03 348 1-63 19*03 7*94 1-28 022 106 2-90=98-81 



affording him the formula S^Si-f-SSi. 



The biotite of Sliidianka, near Lake Baikal, has the form of some muscovites, the 

 sides of the tables consisting, according to Kokscliarov (Min. RussL, ii, 145), of two 

 planes [like the two J and e in fig. 409, Min., p. 221], regarded as the two pyramids 

 1 and 2; 0: l=about 107, : 2=99^. In another crystal there is between and 

 1 the pyramid ^; 0:^=132^ nearly. The mica is biaxial, but the angle between 

 the axes is very small. 



A pseudomorph of mica after orthoclase, from Lomnitz, afforded von Rath (Pogg. 

 xcviii, 280): 



^i SI ¥e Ca Sig ]?ra 



1. Mean of results, 4904 2901 556 017 075 050 



2. Unaliered orthoclase, 66 66 1886 46 0-36 21 3 01 



The oxygen ratio for the mica is ft : IS : Si:=l : 4-83 : 10*74. The ratio is peculiar for 

 a mica, being known thus far only in one of uncertain locality analyzed by Ram- 

 melsberg [see Min., p. 224, anal. 8], and a mica pseudomorph after scapolitc anal} zed 



by von Rath [see Min., p. 204, anal. 13, in which place CaC=ll'll should be added]. 



This last analysis, omitting the CaC, becomes 



§i XI J'e Ca % STa «: . fi 

 1. Mica pseud., 49*6 27-6 ■ 150 ■ ■ SO =100 



fi: 



ft ign. 



1M9 



116 349=10087 



11 12 



— 50=10118 





2. UnaltM scapolite, 50-55 2829 5-60 2*43 0-41 1-26 7*62 3'91=: 9997 



[The orthiXilase mica has nearly the artgitie ratio of 1 ; 2 for the oxygen of the bases 

 and silica.] 



MORONOLITE, Shepard. — In Shepard*s Min., p. iv, is the description of some 

 ovoidal or flat concretions under the name moronoUte (from jiwposj a mulberry), Tlie 

 < concretions were obtained from the under side of a mass of gneiss. They have a 



coating of impure hyalite, and with it "is intermixed what appears to be an oxalate 

 and carbonate of lime," of a yellowish color; H.=3o, G.=2'62; in a tube yields 

 water with some organic odon In platinum forceps blackens and becomes mag- 

 netic; the globule after a few hours in the air gathers moisture which has the taste 

 of sulphate of iron. [No reactions are given which prove that oxalic acid is present, 

 and there is no analysis of the substance as to any of its ingredients. It is difScult 

 to see on what its right to being con^^idered a species rests. — J. r>. d.J \ 



Molybdenite [p. 66, and I].— According to Kokscliarov, the crystals of molyb- 

 denite are monoclinic or perhaps trimetria He figures hexagonal plates which are 

 compoMnd crystals made up of six sectors by as many radii, with strlie at right 

 angles to the sides of the hexagon. Min. RussL ii. 



NEPAULITE, PhUmgton.—K mineral described by Piddington in the Joum. 

 Afiiat Soc. Bengal, 1854 (Kenngott's Min. Forsch. ior 1855). Tlie results of the 

 analysis are much against the species. They are, Si 3 60, S 160, BiSi? S4'80, 



Cn and C 22-96, f'eC 25*62, Se 9 40, Ea 2-80 with a trace of silvers 100-78. H. 

 5_6. G.— 4'5. Metallic in lustre, granular, slightly foliated. Powder grayish-black, 

 iiot magnetic. B.B. infusible. Found in masses tliree -fourths of an indi thick, with 

 quartz, orthoclase, a cerium ore, chlorite. 



