368 Mineralogy. 



5. Formulas for the Marifranese Ores. — The species of manganese ores of 

 which complete mineralogical and chemical descriptions were published in 

 this Journal^ No. vii. p. 41-51, and No. xviii. p. 304. and 349, have the 

 following formulas : — 



1. Manganite, - - M n + H 



2. Braunite, - - M n 



3. Hausraannite, - M. n + M n 



4. Pyrolusite, - - M /i 



5. Psilomelane, - if n + x JB a 



(PoggendorfF's Annalcn, vol. iv. p. 221.) - 



6. Measurement of the Crystals of Adularia. — Professor KupfFer at Ka- 

 san has measured crystals of Adularia from the Tyrol with the reflective 

 goniometer, and has found the following angles : — 



T on J? = 118" 48'.6 ; T on P = 112° 16'.0 ; a:, on T = 110° 40.'25 ; 

 ar on P = 129° 40.8 ; P on the axis = 63° 53'.0 ; x on the axis = 65°47'.3. 

 — Poggendorffs Annalen, vol. xiii. p. 209. 



7. Account of Davyne, a New Mineral Species. By W. Haidinger, 

 Esq. — The prismatic form of this mineral is a rhomboid of 112° 16' 

 whose axis is ^i,5y. It is colourless and transparent. Its lustre is feeble, 

 and sometimes pearly. Its hardness is a little greater than that of hepatite. 

 Its specific gravity is 2. 4. It forms a jelly with acids. It is accompanied 

 with brown dodecahedral garnet. It is composed as follows : — 



471. 



8. On Specific Gravity as a Mineralogical Character. By M. Beudant. 

 M. Beudant has determined by many experiments, that the specific gra- 

 vity of the same species when very pure varies perceptibly with the state 

 of aggregation. It attains its maximum in small crystals, and its mini- 

 mum in varieties of a compound structure. Thus the specific gravity va- 

 ries in the following minerals : 



