MINERALS AND GEOLOGY OF CANADA. 175 
‘charcoal with microcosmic salt in a reducing flame, the glass becomes, 
on cooling, deep red. 
Chromic Iron Ore.—This substance is also closely related to Mag- 
netic Iron Ore. It has a black colour, with sub-metallic lustre, and 
dark-brown streak. It occurs commonly in amorphous granular 
masses, and consists normally of sesqui-oxide of chromium and oxide 
of iron. H. 5.5; sp. gr. 4.3-4.6. Bolton and Ham, in the “me- 
tamorphic district’ of the Eastern Townships (where it occurs in 
veins of about a foot in thickness, in serpentine) are its principal 
Canadian localities.. It is found also in other places throughout this 
district, in small grains, in dolomite and magnesite rocks. When 
quite pure, it may be distinguished from magnetic iron ore by its 
brown streak and lower sp. gr.; as well as by its want of (or feeble) 
magnetism. Chromic Iron Ore is used for the preparation of chro- 
mium compounds, employed in dyeing, painting, &c. 
Brown Iron Ore (Limonite).—Brown of various shades, with sub- 
metallic (or sometimes stony or silky) aspect, and yellowish-brown 
streak. Occurs chiefly in botryoidal masses with fibrous structure 
(a variety often called Brown Hematite), and also im vesicular and 
earthy amorphous masses (Bog Iron Ore). H- 5.0-5.5; sp. gr.3.5-4 0. 
Blackens before the blow-pipe, and becomes magnetic. In the bulb- 
tube (fig. 22) it gives off water. One hundred parts contain (if the 
substance be pure): Sesqui-oxide of iron, 85.6; water, 14.4. This 
is likewise a valuable ore of iron. The Bog Iron Ore variety (in 
addition to yellow ochre described in Section D 8) is that which chiefly 
occurs in Canada. This variety is a comparatively recent product ; 
and its formation, indeed, is still goig on in places, by deposition 
from water in the form of carbonate of iron oxide, this being after- 
wards converted into the hydrated sesqui-oxide. It occurs in great 
abundance in Post-tertiary deposits in the Three Rivers District, C.E., 
(yielding the celebrated ‘St. Maurice, or Three Rivers Iron,” largely 
employed for castings); and also in the County of Norfolk, C.W. ; 
besides many other localities. Altogether, the following Townships 
and Seigniories are enumerated by Sir Wilham Logan (Hsquisse 
séologique du Canada) as yielding this ore: Middletown, Charlotte- 
ville, Walsingham, West Gwillimbury, Fitzroy, Eardley, March, Hull, 
Templeton, Vaudreuil, St. Maurice, Champlain, Batiscan, Ste. Anne, 
Port Neuf, Nicolet, Stanbridge, Simpson, Ireland, Lauzon, St. Val- 
lier, &c. These bog iron ores always contain a small amount of 
