J. D. Dana’s Mineralogical Contributions. 211 
103° 38’; and the carbonate and sulphate series differ fundament- 
ally by 10 to 15 degrees. Hausmann therefore cannot be right in 
making the carbonates and sulphates homceomorphons; by assum- 
ing a different prism in Anglesite (one usually taken as a horizon- 
tal prism) as the fundamental vertical prism; the alleged homeo- 
morphism was based on a comparison of parts nob hanolegsth 
and does not exist. This conclusion also follows from the fact 
that the common hexagonal and 6-rayed twins of Arragonite and 
Cerusite, arising from the nearness of the angle of the prism to 
, hever occur in the sulphates, showing that the angle of the 
fundamental prism is not near 120°, 
2. Homeomorphism of Beryl, Pyrosmalite, Dioptase, and 
Eudialyte. s 
0:1 :2 
“Beryl, (Be, AlSiz 150° 3’ 180° 57’ 
Pyrosmalite, 4( ie, eye Bir re or [+Pe fe « . 148° 30" 129° 8” 
Eudialyte, R* Si? Zr 148° 38’ ~—-129° 21” 
Dioptase, Gu? Sis fit : : 148° 38” 129° 21/ 
0 is the basal or terminal sthie} in cack and tis 1P. In Diop- 
tase it is a cleavage plane (1R), and in Budialyte, althongh usu- 
ally designated 4B it is also a direction of cleavage, though im- 
perfect cleavage, and should be taken as 1 
ith the above group, the foliage a may also be seca 
Cinnabar, Hg S, or 36’) O : $=146° 32/ O : 1=127° 067 
Quartz, $i, (R=94° 15’) O : $=147° 85! 0: ean die 13! 
Dreelite, (Ca, Ba) §, omen ) 
Susannite, Pb §+3hb 6, (R=94°) 0: 4=147° 26’ O : 1==128° 03/ 
It is possible that the plane 4 in Cinnabar and Quartz may be 
homologous with that of Lin Dioptase or Beryl. With regard 
to Quariz or Dreelite, there is the objection to this view that they 
do not correspond with Dioptase in cleavage. ‘Taking them as 
here designated, the vertical axis in each is twice that of Ber yl. 
Chabazite also is near quartz in angle. 
3 Homeomorphism of Pyrrhotine (Magnetic Pyrites ae Green- 
an 
ochite, Breithauptite, Copper Nickel, Nepheline, oe yt rinile. 
Pyrrhotine, Fe7 Ss; FeS? QO: 1==185° 16’ O :4=158°? 39° 
- Greenockite, Cas, O :1==136° 24/ O : $=154° 82’ 
Breithauptite, Ni Sb, O : 1==135° 15’ O : 4=158° 38’ 
pper Nickel, Ni As, O : 1=5136° 35/ O : 4==154° 41’ 
Nepheline, (Na, K)? Si-2%1 Si 0 : 1=136° O: J=154° 13} 
ochre and Nepheline are nearly identical in poe'* — 
‘ =< ae from the allied species; O: 159° 10, 
8 : inlay ond O ; 3 in either of the above. 
The expressions here used for the planes are essentially those of Naumann, ct 
mere ‘edhe P is ropped. In the monoclinic system the clino- 
forms are ie Gitingeiahed by by a gfave accent (°). 
