The following analyses, by W. F. Hillebrand, of separations from the gabbro of Ashland County, Wis., were made for the late R. D. Irving, but were never published by him:

H. Magnetite, record No. 687. Partial analysis.

I. Feldspar, record No. 688.

J. Diallage, record No. 686.

For convenience I also include here, although it is decidedly out of classification--

K. Graywacke, Hurley, Wis. Described by Bayley in Bull. 150, p. 84. Analysis by H. N. Stokes, record No. 1314. Contains quartz, feldspars, iron oxides, and probably kaolin. In the cement are chlorite, quartz, magnetite, pyrite, rutile, occasionally biotite, and either muscovite or kaolin. P. R. C. 20.

5. ROCKS OF PIGEON POINT, MINNESOTA.

Described by Bayley in Bull. 109. Also partially in Amer. Journ. Sci., 3d series, vol. 37, p. 54. A and B are also described in Bull. 150, p. 274.

A. Olivine-diabase. Hessose. Contains labradorite, olivine, pyroxene, apatite, and magnetite. Analysis by W. F. Hillebrand, record No. 496. P. R. C. 107.

B. Diallage separated from diabase. Partial analysis by R. B. Riggs, record No. 607.

C. Rock lying between the diabase and the adjacent red porphyry. Adamellose. Contains red feldspar, quartz, hornblende, chlorite, magnetite, apatite, and rutile. Analysis by W. F. Hillebrand, record No. 500. P. R. C. 1018.

D. Red soda granite. Liparose. Contains feldspar, quartz, chlorite, some muscovite, rutile, leucoxene, hematite, and apatite, with sometimes secondary calcite. Granular variety. Analysis by W. F. Hillebrand, record No. 495. Dried at 110°.

E. Same as D, porphyritic variety. Toscanose. Called by Bayley a quartz-keratophyre. Analysis by Hillebrand, record No. 497.

F. Similar red porphyry, Little Brick Island, Lake Superior, near Pigeon Point. Liparose. Consists chiefly of feldspar and quartz, with augite occasionally present. Analysis by L. G. Eakins, record No. 1059.

G. Red feldspar, anorthoclase, separated from D. Contains hematite inclusions. Analysis by J. E. Whitfield, record No. 521. Dried at 104°.

H. Dark vitreous quartzite. Contains quartz, a little red feldspar, some chlorite, some green mica, a few scales of biotite, and grains of magnetite. P. R. C. 1007.

I. Lighter interbedded quartzite. Feldspar in it much altered. P. R. C. 1004.

J. Epidotic quartzite. P. R. C. 1023.

K. Unaltered quartzite. P. R. C. 1006.

Analyses by R. B. Riggs, record Nos. 569, 571, 572, 575. Material dried at 105°.

L. Altered quartzite. Contains more fibrous chlorite, some sericite, a little kaolin and biotite, grains of magnetite, earthy matter, and sometimes a little calcite. Analysis by R. B. Riggs, record No. 570. P. R. C. 1009.

M. Mottled quartzite. Analysis by Riggs, record No. 573. P. R. C. 1021.

N. Purplish slate, containing many small crystals of red feldspar and scales of mica. Analyses by J. E. Whitfield, record No. 520. P. R. C. 1024.

O. Very slightly altered slate. Analysis by Riggs, record No. 576. P. R. C. 1011.

Material for analysis dried at 104°-105°.