B. Granite-porphyry, Wolf Butte. Toscanose. Phenocrysts of quartz, orthoclase, plagioclase, and biotite in a groundmass of quartz and alkali feldspar. A little apatite and iron ore, with secondary calcite, limonite, chlorite, and white mica. Analysis by Stokes.

C. Granite-porphyry, top of Barker Mountain. Toscanose. Phenocrysts of orthoclase, oligoclase, biotite, green hornblende, sphene, and iron ore, in a groundmass of quartz and alkali feldspar. Also a little apatite and some secondary chlorite and limonite. Analysis by Stokes. D. Syenite, Wright and Edwards mine, Hughesville, near Barker. Toscanose. Very fresh rock. Contains magnetite, ilmenite, hornblende, anorthoclase, albite, subordinate quartz, a little chlorite, calcite, and limonite, and white mica in traces. Analysis by Stokes.

E. Syenite, Yogo Peak. Monzonose. Described in Amer. Journ. Sci., 3d series, vol. 50, p. 471. Contains apatite, sphene, iron ore, pyroxene, hornblende, biotite, orthoclase, oligoclase, and quartz, with traces of chlorite and limonite and a little kaolin. Analysis by Hillebrand.

F. Syenite-porphyry, dike at head of Sheep Creek. Toscanose. Phenocrysts of orthoclase, some plagioclase, and green hornblende, in a groundmass of alkali feldspar, with some quartz. Also contains a little apatite and iron ore, with some secondary calcite and kaolin. Analysis by Hillebrand.

G. Syenite-porphyry, intrusive sheet, between Yogo Peak and Big Baldy Mountain. Lassenose. Abundant phenocrysts of hornblende and orthoclase, with less biotite and plagioclase, in a groundmass of alkali feldspar with accessory quartz. Also contains iron ore and apatite, with secondary calcite, chlorite, sericite, and kaolin. Analysis by Hillebrand.

H. Granite-syenite-porphyry, north end of Thunder Mountain. Toscanose. Phenocrysts of orthoclase, oligoclase, hornblende, and biotite, in a groundmass of alkali feldspar and very abundant quartz. Also contains a little sphene, iron ore, and apatite, very little secondary chlorite and limonite, and a trace of kaolin. Analysis by Stokes. I. Quartz-syenite-porphyry, top of Big Baldy Mountain. Toscanose. Phenocrysts of orthoclase, plagioclase, biotite, iron ore, brown hornblende, and sphene, in a groundmass of quartz and alkali feldspar. Also contains a little apatite, with traces of chlorite, limonite, and kaolin. Analysis by Hillebrand.

J. Syenite-diorite-porphyry, talus slope on west side of Bear Park. Dacose. Phenocrysts of biotite, hornblende, plagioclase, and orthoclase, in a groundmass of quartz and alkali feldspar. Also contains a little magnetite, chlorite, white mica, and apatite. Analysis by Stokes.

K. Diorite-porphyry, Steamboat Mountain. Adamellose. Phenocrysts of orthoclase, plagioclase, hornblende, and biotite, with a little iron ore and apatite, in a groundmass of orthoclase, plagioclase, and quartz. Analysis by Stokes.

L. Diorite, Carpenter Creek, near Neihart. Andose. Contains green hornblende, biotite, and plagioclase, with some apatite, iron ore, calcite, kaolin, and muscovite, and a very little quartz and orthoclase. Analysis by Hillebrand.

M. Minette, intrusive sheet, head of Sheep Creek. Monzonose. Chiefly biotite, augite, and orthoclase, with accessory apatite, plagioclase, quartz, and iron ore, and some secondary calcite, chlorite, and kaolin. Analysis by Hillebrand.

N. Monzonite, Yogo Peak. Monzonose. Described in Amer. Journ. Sci., 3d series, vol. 50, p. 473, and 4th series, vol. 1, p. 356. Contains apatite, sphene, iron ore, pyroxene, hornblende, biotite, orthoclase, and oligoclase, and a little secondary kaolin. Analysis by Hillebrand. O. Monchiquite, dike on Big Baldy Mountain. Monchiquose. Contains much pyroxene, a few serpentinized olivines, iron ore, and apatite in a colorless base of analcite. Analysis by Hillebrand.

P. Monchiquite, dike on Bandbox Mountain. Near ryomingose. Contains olivine, augite, biotite, analcite, and apatite, with traces of serpentine and chlorite. Analysis by Stokes.

Q. Shonkinite, Yogo Peak. Shonkinose. Described in Amer. Journ. Sci., 3d series, vol. 50, p. 474. Chiefly augite and orthoclase, with a considerable amount of accessory biotite, iron ore, and andesine, less apatite and olivine, and a trace of kaolin. Analysis by Hillebrand.

6. CASTLE MOUNTAIN DISTRICT.

Rocks described by Weed and Pirsson in Bull. 139. Analyses made by Pirsson in the laboratory of the Sheffield Scientific School.

A. Rhyolite, between Fourmile and Fivemile creeks, near Smith River. Liparose. Contains quartz, soda orthoclase, tourmaline, and a little iron ore and zircon. P. R. C. 560.

B. Quartz-tourmaline-porphyry, upper Fourmile Creek. Liparose. Contains quartz, orthoclase, plagioclase, tourmaline, fluorite, and a little white mica, apatite, and zircon. P. R. C. 558.

C. Granite, Elk Peak. Liparose. Contains quartz, orthoclase, oligoclase, biotite, hornblende, iron ore, apatite, sphene, and zircon. The last three minerals are rare. P. R. C. 551.

D. Quartz-porphyry, sheet or ridge between Fourmile and Checkerboard creeks. Liparose. Contains quartz, plagioclase, an untwinned feldspar and biotite, with occasional grains of iron ore and crystals of apatite and zircon. P. R. C. 557.

ose.

E. Rhyolite-pitchstone, forks of Checkerboard Creek. KallerudEssentially glass, inclosing grains of iron ore. P. R. C. 561. F. Aplitic granite, dike between Blackhawk and Robinson. Liparose. Contains quartz and unstriated feldspar, some plagioclase, and occasional biotite. P. R. C. 553.

G. Quartz-porphyry, Musselshell Canyon. Liparose. Contains quartz, biotite, plagioclase, apatite, iron ore, and zircon. P. R. C.

H. Feldspar-porphyry, dike below Castle. Lassenose. Contains orthoclase, less plagioclase, hornblende, biotite partly altered to chlorite, sometimes allanite, and occasional iron ore, apatite, and zircon. P. R. C. 555.

1. Rhyolitic tuff, near forks of Checkerboard Creek. Contains fragments of shale, quartz, plagioclase, sanidine, and hornblende, in a brownish material carrying pumiceous glass. Much decomposed, with formation of kaolin. P. R. C. 562.

J. Syenitic mass included in granite, head of Cottonwood Creek. Akerose. Contains orthoclase, plagioclase, quartz, hornblende, biotite, apatite, and iron ore. A hornblende-mica-syenite. P. R. C. 554.

K. Diorite, between Blackhawk and Robinson. Andose. Contains plagioclase, orthoclase, quartz, biotite, diallage, hypersthene, iron ore, apatite, and zircon. P. R. C. 559.

L. Basalt, Volcano Butte. Kilauose. Contains labradorite, augite, olivine, a little serpentine, occasional quartz grains, small patches of glass, iron ore, chiefly ilmenite, apatite, a trace of calcite, and a mineral which may be nephelite or analcite. P. R. C. 565.

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. Contains augite, olivine, biotite, ilmenite, and a colorless base which appears to be partially zeolitized glass. Also a little serpentine, chlorite, and calcite. P. R. C. 564.

a Unseparated rare earths or metallic acids, such as columbic, tantalic, etc.