TO 
MUSEUM BULLETIN NO. 27. 
from one-eighth to half an inch ; they are composed of compact material, 
with only a very thin, imperfectly crystalline crust on their surface. 
No individual crystal flakes were observed on any of the specimens, but 
the crust was identified with certainty as colerainite, by its optical 
characters. 
Much of the compact matrix is white with a surface recalling unglazed 
porcelain, as in the old Standard mine specimens, but here it shows a 
greater tendency to concentric banding. Immediately adjacent to the 
crystalline crust the material is commonly translucent and nearly 
colourless, and this zone is followed by banding in white, pale cream, 
and pink. Altogether, the specimens have very much the appearance of 
banded chalcedony and at first, indeed, they were assumed to be this 
mineral. The lustre is either dull, like that of chalcedony, or waxy, like 
common opal. The hardness is 2| to 3 and the specific gravity, as deter- 
mined on several pieces by the heavy liquid method, is 2 • 34-2 • 35. 
The compact material, with as little as possible of the crystalline 
crust attached, was analysed by M. F. Connor with the result given in 
column 1 below. 
Union pit 
Loganite, 
Calumet falls 
Pseudophite, 
Berg Zdjar 
SiO*. 
33-00 
13-12 
33-28 
13-30 
1*92 
33-42 
15-42 
ai s 6*. 
FejO* 
2-58 
FeO 
CaO. .......... 
Trace 
35-30 
0-11 
0-15 
2-55 
16-12 
35-50 
34-04 
MgO 
K*0. ........... 
Ma*0 
jl6-00 
12-68 
H *0—108® 
HtO+108® 
100-35 
100-00 
98-14 
This analysis differs from those of the old Standard mine material 
mainly in showing a higher content of Si02 and lower A1 2 0 3 . There 
can be no doubt, however, that this material is closely related to that 
which forms the matrix of the old Standard mine specimens, and it is 
very probable that in both cases it is not a homogenous mineral. The 
composition, as calculated from the analysis, is roughly 8Mg0.Al 2 0*. 
5Si0 2 .9H 2 0; if it is assumed that the material analysed was in part 
colerainite, then this might have been mixed with a hydrous magnesian 
silicate of composition 4Mg0.3Si0 2 .4H 2 0, near serpentine, or “aphro- 
dite,” which approximates to MgO.SiO 2 .H 2 O. In its blowpipe char- 
acters and behaviour towards hydrochloric acid, the Union pit material 
resembles that from the old Standard mine; this further suggests the 
essential identity of the two occurrences. 
