212 = J. D. Dana’s Mineralogical Contributions. 
These species have O:1 nearly coincident with O:2-2 in 
beryl (2-2, or 2P2 being a plane on the basal angle of the hexag- 
onal prism). Hence if the series of planes on the angles in Ne- 
pheline and others of this group is homologous with that on the 
edges in Beryl, the two groups would be properly united. But 
there is no good reason for this supposition. Taking the planes” 
as presented, the vertical axis in the Beryl group is to that in the 
y 4 
~~ 
Nepheline as v5: 4. 
4. Homaomorphism of Willemite, Phenacite, and the species of 
the Corundum Group. 
y Weainliet 2008 Bh eh ie Oe, on gt 
Phenacite, Be Si - Ri ees “ a R=116° 40’ 
These angles are the angles of $R in the Corundum Group, 
and may be reasonably taken as of 4R in Willemite and Phena- 
cite. 3:4 in Specular Iron=115° 22’, Oxyd of Zinc (Zn) 18 
shown by G. Rose (Kryst.-Chem., p. 64) to have the form essen- 
tially of Corundum ; and water (If) is probably of this group. 
Corundum has for O : R, 122° 26’, being 4° 40’ less than in Cin- 
nabar, and nearly 6° less than in Quartz. 
5. Homaomorphism of Apophyllite, Nagyagite, Uranite, Ana- 
tase, Matlockite. 
These species have a more or less perfect basal cleavage. 
Ost 
Apophyllite, (Ca, K)SitoH — - - “ 119° 30° 
Nagyagite, (Pb, Au) (Te, 8)? ne ee - 118° 37’ 
Uranite, Oa B+ 82 Bie - - - 118° 35’ 
5 natase, Ti - - . - és 119° 99° 
Matlockite, Pb Ci+-Pb O - - - 119° 34” 
Hausmannite (Mn ¥n) is stated to be homceomorphous with 
Anatase ; its angles diverge more widely than the others from the 
type, O: 1 giving 121° 3’. It is intermediate between this grouP 
and the Idocrase series. Calomel has 0: 1=119° 51’. But = 
cleavage is not basal. : 
The Zircon group, which includes Zircon, Rutile, Cassiler 
ite, Eirsiedite, have the vertical axis twice that of the grouP 
above. O: 1 in Zircon=137° 50’, and O : 2=118° 54’. eagied 
if the plane 1 in the Apophyllite series may be taken as 2, ¥ 
groups come together. it 
may be of the Zircon type. O:1 in Scapolite is 148° 20’; — 
So that if the prism of most perfect cleavage in Scapolite be 
taken as the fundamental prism, and 4P o becomes 4P, the tw? 
angles. . eae 
