Mineralogy and Petrography. 11 
r Stoneham, Maine, in the destriti 
dition to the facts announced in the former notice it may be added 
that the mineral is orthorhombic with <z ; <^ .• ^ == .5724 : i :^490. 
It has four cleavages parallel respectively to o P, 00 P^, co P3 and 
00 Ps^ in the order of their perfection. Twins parallel to co P are 
not rare. It is colorless or yellow and transparent. The plane of 
its optical axes is 00 P55-. Its double refraction in negative and 
2 Ha = 72° 47' for yellow light. The mineral is remarkable for the 
presence in it of cavities elongated parallel to the c axis. These 
sometimes contain two movable bubbles, and are so numerous as to 
produce an apparent columnar structure in the mineral. — Dahlite 
from Bamle, Norway, is described by Brogger and Backstrom^ as a 
new mineral occurring as a thin yellow crust on massive apatite. 
This crust is composed of little fibres arranged perpendicular to its 
surface, which is smooth and lustrous. The mineral is translucent, 
is optically negative, has a hardness of about 5 and a specific gravity 
of Z-'^SZ- It is a hydrous double phosphate and carbonate of cal- 
cium (4 Cas (P04)2 + 2 Ca CO3 + H2O) It gave on analysis : 
P^Og CO.3 CaO FeO Na^O KjO H2O 
38.44 6.29 53.00 .79 .89 .11 1.37 
Aivaridte^ is the first nickel-iron compound described that is not 
of meteoric origin. It occurs in small plates and granules in the 
sand of George River, in the western part of South Island, New 
Zealand. Its composition is : 
Ni Co Fe S Si 
67.63 .70 31.02 ,22 ,43 
The mother rock of the mineral is a serpentine that has origin- 
ated from an olivine rock by alteration.— Darapsky^ adds Naposite 
to the list of iron sulphates from Atacama, Chili. It is found in 
radially fibrous, glistening, brittle, dark-red crystals containing 
24.72 percent, of SO3, 30 per cent, of FcgOg, and 16.43 per cent, of H'O, 
thus cor'responding to the formula Fe (FeOg SG 43, + 10 H2O It is 
decomposed by water and by 2iC\ds,—Mazapilite. Dr. Konig' an- 
nounces the discovery of a new arsenide of calcium and iron from 
Zacatecas, Mexico. It occurs in dark red and black, probably or- 
thorhombic crystals, with a hardness of 7 and a specific gravity of 
3.567. 
corrosion figures 
Aefv. Vet.-Ak 
:ad. Forhandl. 188S, d. 493. Ref. Am. Jour. Sci. 
Jan. '89. 
. Xeues Jahrb. f. Min., etc.. iSSo, I. p. 23. 
5c. Xac. Min., Santiago de Chile, Ref. Neues . 
Jahrb, f. 
1. Min.. 18S8, XI., p. 269. 
