50 ANALYSES OF ROCKS AND MINERALS, 1880-1908. 
D. Schistose quartz porphyry. Toscanose. Contains quartz, feldspar, sericite, 
some chlorite, anatase, and tourmaline, with zircon and apatite sparingly. A, B, 
and D are from the Wisconsin side of the river. : 
Analyses by R. B. Riggs, record Nos. 392, 393, 394, 395. Material dried at 105°. 
SCHIST FROM THE ARAGON IRON MINE. 
Described by Bayley in Mon. XLVI, p. 122. Consists of quartz and micaceous 
minerals, either talc or kaolin and serpentine. Some limonite is present. Analysis 
by George Steiger, record No. 1835. 
GO: AbOVO1 10": 3. ocict cine iaweseeeceoreen 7.66 
5. PENOKEE-GOGEBIC REGION. 
Rocks mostly described by Van Hise in Mon. XIX. Analyses A to G by T. M., 
Chatard, record Nos. 991, 992, 993, 994, 995. 
A. Diabase, near southeast corner of sec. 18, T. 47 N., R. 46 W., Michigan. Auverg- 
nose. Contains plagioclase, augite, magnetite, apatite, and olivine, with some ilmenite 
and leucoxene. P. R. C. 1001. 
B. Same dike as A, partly altered. The pyroxene is altered to amphibole, and the 
latter partly to biotite. Buiotite has also been derived from feldspar. P. R. C. 1000. 
C. Feldspar separated from A. 
D. Altered diabase, Aurora mine, NE. { SW. }sec. 23, T. 47 N., R. 47 W., Michigan. 
P. R. C. 1002. 
100.12 | 100.15 | 100.24 | 100.85 
