B4 ANKERITE VEINS OF 'LONDONDERRY—LOUIS. 
This ore occurs in deposits having the same average direction 
as the Ankerite veins, (namely, from 5° to 10° N. of W.,) and it 
mostly runs out in descending into Ankerite or, more frequently, 
Sideroplesite. Rounded boulders of both of these minerals are 
not uncommon in the “ Red ore.” 
Red ore is amorphous and earthy in fracture. It is often 
very distinctly pseudomorphous, after Ankerite or Sideroplesite, 
when the cleavage planes of the original mineral are very evi- 
dent in the Red ore and are indicated by a strong satiny lustre. 
The hardness of the ore is between 2 and 3: its colour varies 
trom deep red through all the shades of reddish-brown to pale 
brown, the red colour being by far the most common, and the 
clear brown comparatively rare. The following analyses will 
serve to indicate its general character. Analysis No. I was made 
on a deep red specimen, and No. II on a brown specimen of the 
ore, both showing distinctly the cleavage planes ef the eriginal 
mineral :— 
L. LL, 
Tmsoluilole, Matter picks o spo ecu BT: 
ANamina <,.J5' i be panacea: trace. trace, 
Mermei@midel tkisc sainile none 87.21, /) Soaon 
Trimanganic Tetroxide..... sa (hh OG 1.85 
annie icls Lata s Sa ney eee . trace. trace. 
MGs ME SUA NLGNE Vie coph Su tave te ob de 0.45 0.65 
Combined:;Water : sccci--6 cs See LOL 10,18 
Flhiosphoric: Acids 1.» aiecneye trace. trace. 
| 100.05 99.60 
It will be seen that the composition of these, like all the Lon- 
donderry ores, is approximately that of Geethite, namely, Fe2 Os; 
H, O; they are, however, not only very ditferent from the ordin-| 
ary brown Heematites of this locality in appearance, but differ 
also in containing less siliceous matter and phosphoric acid. It 
is very difficult to assign these Red ores to any definite mineral 
species, the characteristics of the bright red variety being espe- 
cially puzzling. While it differs from Turgite, in containing 
nearly twice as much water of hydration, and in not decrepitat- 
Rs + teoce —: 
