16 
These specimens of halotrichite appear to be vein material. They 
display a columnar structure and certain parts of their mass carry con- 
siderable disseminated iron pyrites and some massive and crystallized 
gypsum. This halotrichite, when fresh, looks somewhat like asbestos. 
It forms greenish white, silky fibres, several inches in length, but unfor- 
tunately, when exposed to ordinary atmospheric conditions, it soon becomes 
yellowish, dull, and pulverulent. The mineral tastes inky-astringent, and 
is essentially composed of sulphur trioxide, alumina, iron protoxide, and 
water. The halotrichite under consideration has a large extinction angle 
and the following indices of refraction: 
a = 1-482 ± 0*003; 7 - 1*487 ± 0*003. 
TREMOLITE CRYSTALS FROM ADMASTON TOWNSHIP, 
RENFREW COUNTY, ONTARIO 
Amongst several specimens collected by F. J. Alcock from a zinc 
prospect on lot 2, concession III, Admaston township, Renfrew county, 
Ontario, there was one of special interest. It consisted of an association 
of ealcite, tremolite crystals, feathery tremolite, and a little sphalerite. 
The tremolite crystals measured up to 1 cm. in length and were colourless, 
white, or greyish. On the two-circle goniometer a few crystals yielded the 
following forms : 
a (100), b(010), ra(llQ), e(130), 1(101), r(fll). 
These crystals are optically negative. The maximum extinction angle 
in the vertical zone is 16°. The axial plane is parallel to b(100) and p was 
found to be 1-622. The optical properties of the feathery tremolite do 
not differ from those of the well-crystallized variety. 
It was observed that the tremolite crystallized before the deposition 
of the sphalerite. 
YELLOWISH BARITE FROM PORT ARTHUR, ONTARIO 
The specimen containing the barite here described consisted of an 
association of green, purple, and colourless fluorite, white massive barite, 
and crystals of yellow barite. The locality as given by the collector, Mr. 
T. L. Tanton, is the west boundary of the city limit of Port Arthur. 
The yellow barite crystals are excellent material for goniometer 
measurements. They have the common tabular habit, and although 
small, some individuals measure one centimetre in diameter. The prism 
zone is missing or is represented by mere truncations. The base and the 
domes are the predominant forms. The following forms were identified: 
b(010), a (100), m(110), n(120), d(102), 1(104), o(011), c(OGl). 
The indices of refraction determined by the oil-immersion method 
were found for sodium light to be: 
a - 1*637 ± 0 003; 0 - 1*638 ± 0*003; 7 = 1-648 ± 0*003. 
ALUNOGEN FROM VERNON, B.C. 
The specimens holding alunogen were collected by Mr. James L. Silver 
and were said to occur near Vernon, B.C., in a vein 9 inches wide. The 
material is not uniform in mineral composition. Quartz, epsomite, and 
