18 G. J. Brush on Hortonolite. 
crystals have a black coating and are quite dull. In large — 
masses the mineral is sometimes nearly black, but on the thin 
edges by transmitted light the color is almost honey-yellow. 
} 
. 
d 
i 
4 
Minute specks of magnetite are disseminated through the mass — 
with occasional flakes of graphite. The crystals are some- 
times imbedded in calcite, as also associated in cavities with 
dodecahedral magnetite. They are frequently half an inch 
long by one quarter broad and one eighth of an inch som 
in some instances much larger. H. = 6:5. Sp. — 
Before the blowpipe in the closed tube no change takes "tale ; 
in the ag tube and on charcoal the mineral becomes dull an 
magnetic, and fuses in the platinum forceps at 4; with borax 
and salt of phosphorus, it reacts for iron and silicic acid, and 
with soda for manganese. The pulverized mineral forms ‘with 
chlorhydric acid a gelatinous mass and is almost completely — 
decomposed. Qualitative analysis showed the presence of silica, 
protoxyd of iron, and magnesia, with a minute quan- 
tity of potash ‘and a trace of lime. It was found by pul- 
verizing the mineral and suspending the fine powder in water 
in a beaker and stirring with an electro-magnet of soft iron, 
that the magnetite could be completely separated from the sili- 
cate. Two quantitative analyses made on material thus pre- 
pared gave Mr. betes G. Mixter— 
2. Mean. Oxygen. 
Silica, 38°52 33°66 33°59 17°91 
Ferrous oxyd, 44°28 44°46 44°37 9°85 } 
Manganousoxyd, 4°72 3°98 4°35 "98 
Magnesia, 16°79 16°56 16°68 6°67 } 17°56 
ime, trace trace 
Potash, 30 "47 39 06 
Ignition, "26 26 "26 
99°87 99° en 99°64 
A. spectroscopi 
solution showed sodium, potas init ealoniur Kents only. 
direct determination of the none of iron on mineral selec 
