150 The American Naturalist. [February, 
Narsisik. Neptunite is a black titano-silicate of iron, manganese, soda, 
and potash, which is found on the surface and in fissures in eegerine 
crystals, in crystals varying from microscopic dimensions to five centi- 
meters. These crystals, which are monoclinic, exhibit the following 
forms : (100), (010), (001), (110), (301), (201), (111), (221), (512) and 
(111) ; the forms (001), (110), and the pyramid (512) proio Rina. 
The axial ratio is a:b:c:= 1.31639: 1: 0.8075 and @= 64° 2%. 
Twinning is very rare with the base the Siiniing plane. Cleavage is 
distinct parallel to the prism, the cracks meeting at 80° in sections 
normal to ¢. The specific gravity is 3.234 and the hardness 5-6. The 
plane of the optical axes is normal to the plane of symmetry and the 
acute bisectrix makes 18° with the vertical axis in the obtuse angle £. 
The absorption is ¢ deep red brown, + yellow red, and a bright red, 
with e>s>«a. Written empirically the formula of the mineral is 
(¢Fe+3Mn) ({Na’+iK,)Si, Ti O. The interfacial angles never 
vary more than 10° from the corresponding angles of titanite, which 
leads Flink to think that neptunite and titanite are isomorphous. 
Epididymite is dimorphous with the eudidymite of Brogger, the 
empirical formula of both minerals being H Na Be SiO, Epididy- 
mite is orthorhombic in symmetry, whereas eudidymite is monoclinic. 
The axial ratio of epididymite is a:b:c¢ = 1.7367 : 1 : 0.9274. The 
forms observed were (100), (010), (001), (110), (810), (210), (201), 
(403), (401), (101), (804), (203), and (221). The crystals are col- 
umnar parallel to b, and the cleavage is perfect parallel to the base 
and less perfect parallel to the macro-pinacoid. H==6. G=2.548. 
The mineral is colorless. The plane of the optical axes is the base 
with a coincident with a the acute bisectrix. The optical angle calcu- 
lated from measurements of the indices of refraction is 2V,—31° 4’. 
The relation between epididymite and eudidymite would seem to be 
somewhat similar to that existing between the monoclinic and triclinic 
feldspars of the same composition. 
Other minerals described from the locality are Xatapleite (hereto- 
fore found only at Langesund), sgerine, Arfedsonite, quartz, ortho- 
clase, albite, eudialite, zircon, epidote, Zinnwaldite, microlite, and 
el pidite. 
Crossite. Palache’ has examined the “ glaucophane” of some rocks 
from the Coast Ranges and finds it to differ so much from the known 
occurrences of glaucophane, that he proposes to call it crossite. The 
occurrence specially studied is in a boulder from the west slope of the 
Contra Costa Hills near Berkeley, Cal. Crystals of the mineral show 
7 Bull. Dept. Geol. Univ. of California, i; pp. 181-191, pl. 11, 1894. 
