1 82 The Amefica?i Geologist. September, is9y 
Origin of Palcotrochis. By J. S. Dillkr. Am. J. Sci., 157,337-342. 
A summary of the reviews of previous writers, and descriptions of 
both the macroscopic and microscopic characters of specimens from 
Mexico (see preceding review), and from the San Christian Gold 
Mine of North CaroHna are given in some detail. In both cases the 
Palcotrochis occurred in igneous rock, the analysis of the North 
Carolina type, which is given in full, indicating a rhyolite. The more 
perfect Palcotrochis are composed of granular quartz and were de- 
posited within the more or less elongated spherulites with which the 
rock abounds, but whether this deposition followed soon after that 
of the spherulites in the course of consolidation, or took place in hol- 
low spherulites (lithophysae), or were the result of subsequent altera- 
tion, is not clear. The biconical forms suggest that they may have 
originated as two spherulitic sectors, of which the apices were the 
centers from which the growth started. M. L. F. 
On the Association of Argillaceous Rocks with Quartz Veins in 
the Region of Diamantina, Brazil. By Orville A. Derby, Am. J. 
Sci., 157, 343-356. 
The paper discusses in detail the characters and probable origin of 
certain more or less strongly decomposed rocks of the Diamantina 
district. An exhaustive analysis of a cyanitic schist from the region in 
question, made by W. F. Hillebrand, is included, M. L. F. 
Goldschmidtite, a New Mineral. Bv William H. Hobbs. Am. 
J. Sci., 157, 357-364- 
The new mineral, to which the name of goldschmidtite has been 
given by the author, is a brittle, silver-white substance, having a 
hardness of about 2 and a specific gravity of 8.6. It is found in the 
form of minute columnar monoclinic crystals attached to the chalce- 
donic coatings of the fragments of a brecciated igneous rock of the 
acid type occurring at the Gold Dollar Mine, Arequa Gulch, Cripple 
Creek. The analysis shows the presence of 31.41 per cent of gold, 
8.90 per cent, silver, and 59.64 per cent, tellurium, corresponding to the 
formula Au^AgTce, and giving it a position intermediate between 
calaverite and sylvanite. Twenty-two crystal forms were recognized, 
ten of which are also recognized in sylvanite, to which the new min- 
eral is most closely allied. M. L. f. 
On a Hydrouiica from New fersey. By F. W. Clarke and N. 
H. Darton. Am. J. Sci.. 157, 365-366. 
This golden-bronze mineral, which differs widely from any hitherto- 
described mica, is found mainly as thin coatings in veins of calcite adja- 
cent to the diabase wall rock at Rocky Hill, N. J. The analysis indi- 
cates an orthosilicate of the formula 
(KH)6s(MgFe)24(AlFe)M(SiO)oT.28H.O, 
pointing to a mixture of muscovitic (R"'(Si04)3R'3) and phlogopitic 
(R"'(Si04)3R"3H3.3H:0) molecules in the ratio of 9 to 5. M. l. f. 
Iowa Geological Survey^ Volume IX: Annual Report, i8g8, with 
Accompatiying Papers. Samuel Calvin, State Geologist; H. F. Bain, 
