DEc., 1908. MINERALOGICAL NOTES I51 
reflecting goniometer. Probably the most remarkable feature ex- 
hibited by the crystals is their apparently hemimorphic develop- 
ment. This development is shown in Figs. 3 and 4, Pl. LI. Thus 
the crystal shown in Fig. 3, Pl. LI, exhibits at one end a small basal 
plane with several modifying pyramids, while at the opposite end 
the basal plane alone occurs. Again, the crystal shown in Fig. 4, 
Pl. LI, shows one end considerably modified by pyramids, while the 
other possesses no modifying planes whatever. Such crystals might 
be expected to show pyro-electricity but careful tests for this property 
made with the kindly assistance of Prof. R. A. Millikan, of the Uni- 
versity of Chicago, gave no indications of its presence. The apparent 
hemimorphism is perhaps therefore to be regarded as due to distortion 
only. Other interesting illustrations of distortion or merohedrism 
are shown by the crystals. Thus on the crystal shown in Fig. 3, Pl. 
LI, but a single plane of the pyramid v (117) occurs, while the other 
forms are present in normal number. ‘The crystal shown in Fig. 4, 
Pl. LI, exhibits two planes of the pyramid v (117) and two planes of 
the pyramid r (115). In addition occur two planes only of the dite- 
tragonal pyramid s, (5.1.19). On the crystal shown in Fig. 2, Pl. LI, 
a single plane of the pyramid of the second order G (104) occurs and 
a pyramid new to octahedrite, M (338) is present as two planes, while 
the development of the other-pyramids is normal in character. No 
differentiation of the planes in luster or etching figures can be noted 
except that the pyramid of the second order G (104) shows numerous 
pittings. In addition the dominant pyramid p (111) is always charac- 
terized by striations parallel to the base. The total forms’observed 
with angles follow, the one marked with an asterisk being new. The 
letter G has been given to the form 104, this form having been listed 
by Hintze* but not lettered: 
HA A AR 
ue (OOT) ¢—(1t 5) Sic (FTI TQ) 
G (104) v (x17) as 
p (ur) *M (338) 
Observed Calculated 
ae (TIT) WerGh it) = Rae ate 20. 93h. 
eee 7 (11S) Wy (5), = 53° 14" 53° 22" 
See 17) A» 17) 3 39° 44° 39° 30" 
Pepome (O01) y Ax (104). 3 = 23° 48’ 23° 58’ 
een wee (O07) A. (338) Sih Rees ae a AB ETOL 
Meee 6505-19) A: (1.5.19). = ERY 27° 38’ 
Pena Se  = . (IIT) Ree blo) = Antes AG>E2: 
NS) = (115) Kor (S Sito) = 14° 46’ TAreAT: 
eis ott ~ (x17) Aa Sarg) = ay 23" a Deas os 
* Handbuch der Mineralogie, 1906, Bd. I, p. 1563. 
