15 
For the calculation of <p and p of the new forms 441 and 665 the accepted 
figures were used. 
— 
Calculated 
Measured 
*665 
IP 
45° 00' 
45° 00' 
P 
47° 23' 
74° 34' 
•P 
45° 
45° 
P 
47° 55' 
74° 35' 
•441 
•New forms. 
EPIDESMINE FROM THETFORD MINES, MEGANTIG 
COUNTY, QUEBEC 
This mineral was collected by the writer on the dump of the King 
asbestos pit. It was found in a slightly altered granitic rock which con- 
tained a number of vugs appearing at first to be entirely filled with calcite. 
Examination of the material under the binocular microscope reveals, in 
addition to the calcite, the presence of minute, yellowish white, prismatic 
crystals older then the carbonate. On the edge of the vugs some orthoclase 
cleavages fresh and altered are also visible. 
The yellowish white prismatic mineral which is referred to here as 
“epidesmine” is not available in sufficient quantity to afford a complete 
chemical analysis. By qualitative examination it was found to be an 
hydrated silicate of aluminium and calcium. Sodium and potassium 
were identified by microchemieal tests. The mineral fuses with intumes- 
cence, behaving like scolecite under the blowpipe. Its specific gravity 
after careful manipulation with heavy liquids was found to be 2*16. 
The crystals, which range in size from microscopic to individuals 3 mm. 
in length, are not suitable material for the goniometer. Only the three 
pinacoid are measurable and their interfacial angle is 90°. This mineral 
is biaxial, negative, and orthorhombic. The refractive indices are: 
a = 1*485 ± 0*002 and y = 1*501 ± 0*002. 
These figures are almost identical with those given by Larsen. 1 
Thus the composition and the optical properties of the Thetford 
mineral are those of epidesmine, a mineral from Schwarzenberg, which has 
the composition of stObite, but differs otherwise and was described and 
named by Y. Rosicky and St. J. Thugutt in 19 13. 2 
HALOTRICHITE FROM ASHCROFT, B.C. 
In 1918 Mr. Mandell of Vancouver submitted to Mr. Charles Camsell, 
then geologist in charge of the Vancouver office of the Geological Survey, 
specimens which were eventually transferred to the Division of Mineralogy 
for investigation. Later on, L. Reinecke collected the same substance as a 
loose block in a tunnel on Mr. M. Ahearn's ranch, 17 miles from Ashcroft 
and east of Bonaparte road, B.C. 
’LarseOjE. S.: TJ.S. Geol. Surv., Bull. 679, p. 243. 
*Dana, E. 8.: See Appendix No. 3. 
