204 B. Silliman—Mineralogical Notes. 
and magnetite. The magnetic sand collected in washing the 
gold-out of the crushed vein stone was examined for chromite 
witbout success. 
It is an interesting question, whence came tlie chromic acid ? 
Perhaps an analysis of the galenite may detect chromium in that 
species. Smith has described a meteoric chromium sulphide, Dau- 
bréelite,* and there is no chemical reason why this species may 
not coéxist with galenite. In the paragenesis of the chromates 
in this district the change has evidently proceeded from without 
inward, and the occurrence of specimens in which the whole of 
the galenite is transformed is not unfrequent, as also the change 
of the crocoite to the lemon-yellow phoenicochroite. 
Small orange-yellow crystals occur in the vauquelinite of the 
Vulture region, which may be the joussite; but more study 1s 
required before they can be proved to be this mineral. 
n conclusion I will add that before the study of these inter- 
esting localities can be complete a personal visit must be made 
by a mineralogist to the mines, and sufficient material obtained 
on the spot to allow of chemical analyses.. 
2. THENARDITE FROM Rio VerpE, Arizona TERRITORY. 
Some months since I received a lump of a saline mineral 
marked “Salt,” reported by my informant, Mr. Treadwell, of 
Pheenix, to occur in abundance on the River Verde, in Maricopa 
County. It proved, on examination, to be anhydrous sodium 
I. i, 
Unhiomme 2 e202 ee 0:095 0°097 
SO; 56°410 56°310 
CaO 0-120 0°130 
M ¢ 
Na,O [42-964] [43-070] 
Insoluble 0-390 0°370 
100-000 100-000 
I. Na,O: 80, = 6°91: 7-02; IL -Na,O: SO; = 6°93: 7°01. 
The mineral is therefore nearly pure Na,SO, The insoluble 
matter out, the impurities are only 0-24 per cent of the mass 
The specific gravity of a fragment quite free from visible 
impurity, taken in petroleum, I find to be 2°681. This mineral 
occurs in large masses, some of which, in the rough, are 
distinctly crystals with imperfect faces, showing eminent cleav- 
age in the direction of the basal plane of the prism and 4 
hackly cleavage in the opposite direction. The “insoluble 
* This Journal, ITT, xii, 109. 
