IGNEOUS AND CRYSTALLINE ROCKS. 87 
M. Augite vogesite, dike on west side of upper Fourmile Creek. Kentallenose. 
Contains augite, hornblende, iron ore, a little plagioclase, orthoclase, calcite, and some 
decomposition products. P.R. C. 563. 
N. Monchiquite-like dike rock, west side of upper Willow Creek. Ourose, Con- 
tains augite, olivine, biotite, ilmenite, and a colorless base which appears to be par- 
tially zeolitized glass. Also a little serpentine, chlorite, and calcite. P. R. C. 564. 
@ Unseparated rare earths or metallic acids, such as columbic, tantalic, etc. 
7. HIGHWOOD MOUNTAINS. 
Rocks collected by W. H. Weed and L. V. Pirsson, and described in Bull. 237. 
Analyses A to N, inclusive, made in the laboratory of the Sheffield Scientific School, 
under the direction of Professor Pirsson. 
A. Trachy-andesite, head of north fork of Willow Creek. Adamellose. Contains 
hornblende, biotite, iron ore, apatite, plagioclase, and orthoclase, with a little kaolin 
and limonite. E.B. Hurlbut and B. Barnes, analysts. P.R.C. 1492. 
B. Tinguaite porphyry, dike 1 mile north of dividein Highwood Gap. Highwoodose. 
Contains abundant phenocrysts of orthoclase and augite in a groundmass of the same 
minerals; also a little biotite, apatite, and iron ore, and some secondary kaolin. E. B. 
Hurlbut, analyst. P. R. C. 1493. 
C. Sélvsbergite porphyry, dike north end of South Mountain. Pulaskose. Contains 
phenocrysts of alkali feldspar, eegirine-augite, and melanite, in a groundmass of alkali 
feldspar. Apatite, iron ore, a trace of calcite, and some kaolin are also present. H.W. 
Foote, analyst. P. R. C. 1494. 
D. Gauteite, dike on Aspen Creek. Monzonose. Contains alkali-hornblende and 
alkali-feldspar phenocrysts, in a groundmass of alkali feldspars; also some apatite and 
iron ore. Rock stained by limonite. H.W. Foote, analyst. P.R.C. 1495. 
E. Syenite porphyry, dike at head of Shonkin Creek. Borolanose. Contains 
augite, biotite, iron ore, and orthoclase, in a groundmass of alkali feldspar; also apatite 
and some kaolin. W.M. Bradley, analyst. P.R. ©. 1496. 
