404 Mr. WHEWELL. on the Classification 
RHOMBOHEDRAL SYSTEM. 
Example and Figure. Class. Combination. 
Class IT. pR,gRm 
No. 5. 7qR,qRe 
Rh’. Lime-haloide 4R,R5 
Mohs, Vol. 11.116. m y 
generally 
3m+1 
< qR, gRm 
No. 6. &qR, qR2 
Rh'. Ruby-blende R,{R3 
LT At26se Peeve 
generally 
3m—1 
gR,qgRm 
2 
generally 
3Sm+1 gk’, Ge 
2 
Class IIT. pR, qRr 
If the angles of a regular 
prism with a pyram’. term™. 
be truncated by rhombs, the 
pyramid and truncating py- 
ramid are pRr, pR, or it 
may be pRr,pR’, or both, | 
Rh’. Quartz R, Rr No. 1. pR, pRr 
IT. 145. $s -2 
pR,pRr, oRr 
Rh’. Corundum R, 2Rr | No. 2. pR, 2pRr 
1 sel ell oh Nc 
If alternate edges of a re- 
gular pyramid be truncated, 
truncating rhombohedron and 
pyramid are pR, 2pRr. 
