930 General Notes. 
occurs,is always associated with these alteration products. It occurs in 
the serpentine, which is directly connected with the grains of olivine 
from which it has been derived. rere is every reason to believe 
that the nickel silicate came from the same source. A study of the 
Webster Co., N. C., and the New Caledonia nickel deposits indicate 
the same origin for the ores at these places.—A feldspar from 
Kilima-njaro, similar to that from the rhombic porphyry of Chris- 
tiania, has been analyzed by Fletcher.’ Its composition is :— 
SiO, Al,O, CaO Na,O K,O 
62.17 23.52 2.90 6.80 4.61, 
corresponding to a mixture of the anorthite, microcline and albite 
molecules in the proportions An, Or., Al,..,. The extinction on 
the clinopinacoid is about 4° 20’. On the basal plane it is parallel 
to the clinopinacoid cleavage. In sections cut parallel to the ortho- 
inacoid the microcline structure is visible.—Sandberger? calls 
attention to the properties of the carbonaceous material in the erys- 
talline limestone of Wunsiedel in the Fichtelgebirge, as those of an 
amorphous substance corresponding to the graphitoid of Inostran- 
zeff and Sauer. The hardness of the mineral is 3 and the specific 
gravity 2.207. It yields when burned 1.78 per cent. of ash.—A 
new analysis of spodumene from Brazil leads Jannasch® to the 
results reached by other analysts, and affirms the correctness of the 
formula (Li. Na), Al, (SiO,),.—Brief notes on the six iron sulphates, 
coquimbite, copiapite, quenstedtite, biickingite, stypticite and halotri- 
chite, from Chili, are communicated by Linck® in a letter to the 
Neues Jahrbuch. 
MORPHOLOGICAL AND PHYSICAL MINERALOGY.—Since almost 
all of our knowledge of the morphological properties of markasie 
depend principally upon the measurements of Hausmann and Sade- 
ek, and since these mineralogists disagree in their results, Geh- 
macher” has thought it worth while to measure the crystals in his 
possession, and from these measurements to recalculate the planes 
occurring in them. He finds the axial ratio to be: .7623 : 1 : 1.2167. 
The formulas of the different planes are determined, and other obser- 
vations are made which indicate a monoclinic symmetry for the 
mineral.—Zepharovich’s® measurements of trona crystals from 
Lake Lagunillas, Venezuela, show their axial relation to be: 
* Min. ea ee July, 1887, and Zeits. f. Kryst. xiii., ’87, p. 384. 
. f. Min., i., p. 200. 
me bi Se 
x 
4 i., p. 196. 
§ Neues Jahrb., f. Min., ete., 1888, i:, p. 213. 
1 Zeits. f. Kryst., xiii., 1887, p. 242. 
8 Ib., xiii., 1887, p. 135. 
