ANKERITE FROM SANDHURST, VICTORIA — COOKSEY. 
63 
ANKERITE from SANDHURST, VICTORIA. 
By T. Cooksey, Ph.D., B.Sc., Mineralogist. 
Among the specimens of minerals in the Museum Collection are 
two, which were obtained from the New Chum line of reef, Sand- 
hurst, Victoria, and which had been placed among those of the 
Calcite group. That these were correctly named seemed doubtful, 
as the powdered mineral effervesced very feebly with dilute hydro- 
chloric acid in the cold. A qualitative test showed that both iron 
and magnesia were present in considerable quantity and a complete 
analysis furnished the following results: — 
CaCO, 
... 48*95 
FeCO, 
... 23-12 
MgC0 3 
... 25 01 
Insoluble residue 
3-54 
100-62 
*3016 gram of material was taken for analysis, which on treat- 
ing with hydrochloric acid, left *0107 gram of insoluble matter 
consisting mainly of albite. By subtracting this insoluble portion 
from the total quantity taken, namely ’3016 gram, and calculating 
the results on the amount dissolved, that is *2909 gram, the per- 
centage composition of the three carbonates is found to be : — 
CaCO 3 50-76 
FeC0 3 ... 23-97 
MgCO s 25-93 
Manganese was not present, neither the borax bead test nor the 
fusion with nitre and caustic potash giving the manganese reaction. 
The specific gravity of the mineral is 2-994 (uncorr.) and its 
hardness about 3-5. 
The crystals consist of very fiat rhombohedrons with slightly 
curved faces occasionally striated, and form the lenticular crystals 
with sharp edges frequently seen in calcite and more especially in 
siderite. They are, however, externally slightly altered and the 
