366 ON THE KLAPROTHINE OR LAZULITE OF NORTH CAROLINA. 
Upper Planes over Lower Planes over 
Front edge: Sront edge: 
Ist measurement...... TOO: Ag sca pester sete 100° 
2nd CO Rai ereretetele 99S 9On int eieitate 99° 99' 
3rd hee) walsneystats po te i Hal a 100° 2 
Upper Planes over Lower Planes over 
side edge: side edge: 
ist measurement...... QTE O OE aes 97° 28' 
and COe st epwti re reasaterctie OTPASO! rete dae 97° 26' 
3rd Celie cece vane Dow Gul acres: 97° 21! 
Front Planes over Back Planes over 
middle edge: middle edge: en fee td 
' a ether monoclinic or trime- 
Ist measurement...... ee TOs, so. 134° 4% trie, hese measurements should 
ond ce Gee OAS | LORS inatets 134° 12’ of course correspond. e two: 
sets were taken, however, for 
8rd JIT ROG OG ev esadec 134° 10’ gereater satisfaction. 
Adelmann’s goniometer gave me 100°—100° 30’ over a front edge 5 
97°—97° 30' over a side edge; and 134°—134° 30’ over a middle 
edge. If we look upon the mineral as Trimetric, and adopt the 
angle of 100° as the mean inclination over a front edge, with 91° 30’ 
for the value of the prism-angle (according to general adoption), the 
following angles and axial relations are obtained by calculation: 
P: P (over a front edgey = 100° 
P: P (over a side edge) = 97° 245" 
P: P (overamiddleedge) = 134° 12’ 
x (vertical axis) = 1°652. 
x (macrodiagonal) = 1. 
x (brachydiagonal)= 0. 9741. 
The measurements of Phillips give for the octahedral angles, as 
deduced by Hausmann, 99° 16’ (over front edge), 96° 39’ (over side 
edge) and 136° 20’ (over middle edge). The position of the crystals, 
as adopted by Phillips, is here changed however—his middle edge 
being made a front polar edge, and the reverse. ‘ 
Many of these North Carolina crystals appear to possess another 
form, in addition to those enumerated above. This is the front 
polar or macrodome, occurring generally on two opposite edges only, 
and thus presenting a monoclinie character, but lying sometimes on 
only one edge, and being consequently (if the mimeral be Trimetric) 
