ae 
Si eo ish hin =| 
Geology and Natural History. 161 
gold placers of the surrounding count Its best locality is on 
the northern slope of the Pilot Mountain, especially at the mine 
of Capt. J. C. Mills. 
The crystals are commonly tabular in form, consisting of the 
a planes 1 and (0, though bei sien me also been observed of the 
Som od 
common octahedral habit. few were highly modified. The 
dull ~s striated pare to 1 and 1-7. The prismatic (/) cleav- 
age can often be seen. The crystals are well preserved and unu- 
average a line in thickness. Color from greenish-yellow to black. 
Some few are quite colorless and transparent and would admit of 
polariscopic examination. In only one capes were they found im- 
planted and that was on quartz. They occur loose in the gravel, 
having hae derived from the didatearntion of the local schists. 
The acc mpanying minerals are monazite, xenotime, fergusonite, 
samarskite, zircon, Brodkite and. thirty-five other distinct minera 
species. 
n Urano-thorite.-—-Professor PETER CoLiieER has described 
a Eivorst from the Champlain iron region (exact locality un- 
known), which is closely related to pot Ri pe but differs 
in containing considerably more uraniu It has a dark red- 
brown co or, a resinous or sub-vitreous " luster, yellow-brown 
streak and sub-conchoidal fracture. Hardness about 5; specific 
gravity =4°126. It is infusible before the blowpipe. An analy- 
sis yielded :— 
SiO. ThO, 020s — Al,0s AY CaO MgO Na,O H,O 
1938 52°07 996 4-0 03 0-4 234 004 O11. 11°31=99°95 
€ name given to er ier has reference to the large 
amount ‘of uranium presen Bese contains 1°6 p. ¢., according 
to Berzelius.— Journal ae ve 2. Soe., vol. ii. 
24. Mineralojia por Ianac ee Yko, Profesor de Quimica i 
Mineralojia en la Uuiversdake da Santiago de Chile. Third edi- 
tion. 762 pp. with 6 plates. Santiago, 1879.—The preceding edi- 
in 1860. Since that time he has published five Appendixes to 
this work, in addition to numerous articles printed in different 
scientific journals. It is consequently a great convenience to 
oe to have this new edition, in which the large num- 
r of new facts, due mostly to labors of the author himself, are 
incorporated, The minerals of Chili and the neighboring repub- 
lics are in many cases of peculiar interest, and for our knowledge 
of them we are indebted almost entirely to Professor Dome ko, 
whose unwearying and most successful activity in investigation, 
far removed as he i is — the scientific centers of the world, is 
gota of high pra 
Las Pavieies U. stones de la Republica rar oe Fe el 
Dr. D. uis BrRackEBuscH. 117 8vo. Buenos Aires, 1879. 
—Dr. Brackebusch has rendered a n important a ts Me to science 
in publishing in compact form a description of the minerals of the 
