Garnets with Actinolite and Talc. (Garnet rock, p. 72.) Aggregate of red Garnet, harder than Quartz with Pyroxene, insoluble, softer than Garnet; sometimes blue Disthene and green Epidote. (Eklogite, p. 72.)

Disthene, infusible, insoluble, barely scratched by the steel point, with Garnet, and Augite. (Disthene, p. 72.)

Aggregate of Cordierite in hexagonal prisms with a vitreous fracture, blue in certain directions, difficult to fuse, attacked slightly by acids, harder than Quartz; Orthoclase and Garnet. (Cordierite, p. 41.)

Mica, Garnet and Iolite. (Kinzigite, p. 42.)

2. Rocks containing at least one black or deep green element other than Mica.

White rock spotted with black or vice versa. Oligoclase in white, greenish-white, or reddish-white grains, fusible, insoluble; black or deep green Hornblende in grains, very fusible, brilliant cleavage faces forming an angle of 124°; Epidote and Pyrites. (Diorite, p. 69.)

.

Rock similar, white or grayish-white Labradorite, Augite in black grains or in crystals of a vitreous fracture and imperfect rectangular cleavage; crystals of Magnetite; the rock often effervescing in acids. (Dolcrite, p. 56.)

Oligoclase, Quartz, Mica, and Hornblende. (Tonalite, p. 71.) Oligoclase, Mica, Hornblende, rock generally porphyritic. (Kersantite, p. 77.)

Oligoclase, Hornblende, forming a rock sometimes porphyritic, sometimes granular, often showing by its porosity, its analogy to the Trachytes. (Hornblende-Andesite, p. 50.)

Same rock with Augite replacing the Hornblende, sometimes also Peridot. (Augite-Andesite, p. 51.)

Labradorite, Augite, Magnetite, rock impregnated with Chlorite and Calcite. (Ophitone, p. 61.)

White or gray Anorthite, fusible, soluble in HCl depositing Silica, Hornblende of a deep green, and a little Quartz. (Orbicular Diorite, p. 70.)

Granulated rock, often porphyroidal with white Anorthite, and black Augite: Hornblende and Epidote as accessory elements. (Eukrite, p. 61.)

Hypersthene of a brownish or greenish-black, with Labradorite of a greenish-white color. (Hyperite, p. 67.)

Quartz and Tourmaline, the latter black and fusible and in a scoria of the same color. (Tourmaline rock, p. 34.)

Granite with a large quantity of Acicular Tourmaline. (Tourmaline Granite, p. 38.)

B. Effervescing with acids, and formed:

1. Of crystalline limestone which effervesces promptly with acids, giving a solution precipitated by Ammonium Oxalate; or of Dolomite which dissolves with effervescence only with heat.

2. Of a large number of accidental minerals.

II. CONGLOMERATE ROCKS.

Formed of fragments of one or many rocks, generally united by a cement:

Angular fragments of Granite in a matrix which differs only by the color or dimensions of its particles. (Granitic Breccia, p. 39.)

Angular or rounded fragments of Porphyry in a matrix of the same kind. (Porphyritic Breccia, p. 46.)

Fragments of Trachyte in a sort of Trachytic paste. (Trachytic Breccia, p. 54.)

Fragments of Phonolite in a paste of Feldspar more or less Kaolinized. (Phonolitic Breccia, p. 51.)

Débris of Melaphyres, Spilites, Wackes, Ophitone, in a brown, green, or gray paste, like those of the Porphyrics, but with more calcareous matter. (Melaphyre conglomerates and Breccias, p. 62.)

Débris of Basaltic character. (Basaltic conglomerates, p. 56.) Same débris with cement of Palagonite. (Palagonitic Tufa, p. 61.)

Débris of Schistose crystalline rocks in an argillaceous paste (Gneiss and Mica Schist conglomerates, p. 39.)

Fragments of Quartz in a siliceous cement often ferruginous. (Quartz Breccia, p. 94.)

Fragments of Jasper or Flint in a siliceous cement. (Jasper Breccia, p. 94.)

Rounded pebbles of Flint in siliceous cement. (Puddingstone, p. 94.)

Pebbles of Porphyrics more or less altered, argillaceous cement (Psephite, p. 95.)

Quartz in pebbles or grains, particles of clay Slate of Phtanite, with a cement and Silica containing free Carbon. p. 94.)

(Graywacke,

Fragments of Sandstone, Limestone, crystalline schists, with siliceous, argillaceous, or calcareous cement with a surface pre senting rounded projections. (Nagelfluc, p. 94.)

Quartz, Feldspar, sometimes Mica in a cement siliceous, or argillaceous, or formed partly of Heavy Spar or Fluor Spar. (Arkose, Feldspathic Sandstone, p. 92.)

Quartz fragments with calcareous or argillaceous cement. (Sandstone, p. 92.)

Quartz grains, flakes of Mica, with particles of Feldspar, argillaceous cement, colored by oxide of Iron, or Copper carbonates, schistose texture. (Psammite, p. 93.)

Same rock with carbonaceous particles. (Carbonaceous Sandstone, p. 92.)

Grains of Quartz and Feldspar, laminae of Mica with a greenish gray cement of a siliceous, marly character; a solid rock more or less schistose and effervescing in acids. (Macigno, p. 93.)

Grains of Quartz, Calcite, Mica Glauconite; cement calcareous or marly. Rock more friable than preceding. (Molasse, p. 93.)

§ 8. Non-coherent Rocks, with Essential Elements Isolated.

Minute grains of Quartz. (Quartz Sand, p. 93.

Quartz grains with flakes of Mica. (Micaceous Sand.)

Quartz Sand is often mixed with fragments of Garnets, Zircous, Magnetite, etc.

Sand formed of small grains and pebbles of Quartz, Jasper, or Flint (Gravel.)

Pulverulent material or very fine fragments of Trachyte or Pumice. (Trachytic Cinder, p. 27.)

Basaltic rocks equally pulverized, or débris of Volcanic Scoria, (Volcanic Ashes, Lapilli and Puzzulana, p. 59.)

Sand is sometimes formed of grains of Dolomite soluble in hot acids, and giving reactions of Lime and Magnesia (p. 104.)

PART FOURTH.

APPENDIX.

DICHOTOMIC METHOD FOR THE DETERMINATION OF Rocks.*

1 S The rock appears homogeneous. 2.

2

3

4

5

6

7

{

{

{

{

{

It is evidently heterogeneous. 175.

It has a metallic aspect, not removed by scratching with a steel point. 3.

Has a non-metallic appearance, or a metallic lustre easily removed by action of steel point. 9.

On charcoal before the blow-pipe yields sulphurous odor. 4.
On charcoal does not yield sulphurous odor. 8.

Yields a metallic globule, malleable.

Yields a non-metallic globule. 5.

Galena.

The solution of the globule in nitric acid, becomes blue with Ammonia.

The nitric acid solution does not become blue. 6.

The rock has a bronze color.

It is of a brass-yellow color. 7.

Chalco-pyrites.

It is radiated.

The effervescence is abundant. 11.

10 { Effervescence Blow or requiring heat. 25.

The solution in acid leaves much residue. 12.
Leaves but little residue. 17.

*Translated from "Cours Elementaire de Geologie Appliquée," par M.

Stanislas Meunier.