IGNEOUS AND CRYSTALLINE ROCKS. 47 
I. Picrite porphyry, sec. 27, T. 44 N., R. 32 W., northwest of Mansfield. Principal 
minerals serpentine, amphibole, chlorite, ilmenite, all but the last being secondary. 
Analysis by Stokes, record No. 1721. 
K:0........ : i : , trace 
HO at 110°... 123 163 
Ba, Sr, Cl, F, S, SO3 not looked for. 
J. Pre-Cambrian nonporphyritic metabasalt, from the Hemlock formation. Beer- 
bachose. Contains plagioclase, light-green hornblende, epidote-zoisite, chlorite, 
calcite, muscovite, apatite, sphene, quartz, pyrite, and magnetite. 
K. Porphyritic metabasalt, Hemlock formation. Same minerals as in J, with feld- 
spar phenocrysts. 
L. Porphyritic metabasalt, like K. SR. 5 of monzonase. 
M. Metadolerite, large dike in T. 43 N., R. 31 W., east of Mansfield. Auvergnose. 
Petrographic data furnished by C. R. Van Hise. Contains uralite, labradorite, and 
ilmenite. 
Analyses J, K, and L by H. N. Stokes, record No. 1617. 
Analysis M by George Steiger, record No. 1814. 
Ke 
Aga tO ioe cpeisacs ovr ceemrnarineis zieminiianeins: 
H20 above 110° 
Ti 
N. Adinole, sec. 8, T. 43 N., R. 31 W., near Mansfield. Contains actinolite, albite, 
quartz, some chlorite, and epidote. Analysis by George Steiger, record No. 1709. 
O. Spilosite. Contains quartz, feldspar, chlorite, epidote, and a little biotite. 
