is also found associated with other rocks. An important Coal-measure variety, very rich in carbonaceous matter, is said by Bristow to be called Black-band. Some beds of the latter are so rich in carbon, that they can be burned by themselves, and might be classed among the coals.

I. MINERALS OCCURRING AS ROCKS.- Some minerals occur in subordinate masses interstratified with the sedimentary rocks; these, however, are not of very frequent occurrence, minerals in mass more often being found in veins, nodules, or irregular accumulations.

a. Asphalte [Gr. asphaltos], Bitumen, Mineral Pitch.-Colour brownish, blackish, or black; lustre like that of black pitch, odour bituminous, melts at from 90° to 100°, and burns with a bright flame.

Of this rock Dana writes: "Asphaltum belongs to rocks of no particular age; the most abundant deposits are superficial."

b. Pyrite occurs in thin beds, layers, and as nodules.

c. Cinnabar." Occurs in beds in slate-rock and

shale, and rarely in granite or porphyry." -Dana. This observer also states that this mineral occurs as rock-masses, both in unaltered and metamorphosed sedimentary rocks.

d. Boracite "occurs in beds of anhydryte, gypsum, and salt."-Dana.

e. Trona, "in North Africa, forming a rock which is even used for building purposes." -Cotta.

f. Aragonite, with its subvariety Flosferri. "The

most common repositories of aragonite are beds of gypsum, and beds of iron ore (where it occurs in coralloidal forms, and is denominated Flosferri), basalt, and igneous rocks."-Dana.

g. Manganese Ores, generally in the older rocks, but also in surface deposits.

h. Rhodochrosite occurs generally in veins, but at Glendree, Clare, Ireland, it forms part of the surface-deposits.

i. Bole, in subordinate masses, in limestone. j. Opal, or Vitryte, in very subordinate masses. k. Fluorite, and l. Barite, rarely found in beds or layers, often occur as gangue in mineral veins.

m. Ankerite, sometimes as an independent rock. n. Malachite, usually in veins.

o. Melanite, in small accumulations.

p. Galmey, or Calamine, as aggregates in dolomyte.

q. Zincite, r. Galenite, s. Stibnite, and t. Arsenopyrite, rarely occur as subordinate layers, but more generally in veins.

u. Sulphur, in concretions and layers, principally in marl and limestone, also in the vicinity of volcanoes.

v. Wavellite, in subordinate beds or layers. w. Chalcopyrite, usually in veins.

C. Rocks partly mechanically, partly chemically, and partly organically formed. These rocks are always more or less crystalline, and usually occur as subordinate beds, interstratified with sedimentary rocks, but not always.

A. LAMINATED or STRATIFIED COAL.-A more or less

fissile crystalline aggregate of carbonaceous

matter; arenaceous or argillaceous to a greater or less degree.

Most coals do not belong to the Subaqueous rocks; some, however, have been formed mechanically from carbonaceous matter, that was first denuded, and afterwards deposited in the sea, or other waters.

NOTE. At the present day the accumulation of mechanicallyformed coal can be observed. Wherever peat-bogs or even hard coal-beds are exposed to denudation, more especially to marine abrasion, they are gradually carried away to be deposited in seas, lakes, &c., forming stratified more or less arenaceous or argillaceous carbonaceous beds, which eventually must be indurated, forming a hard coal. Some of these deposits in the vicinity of the Irish coast are of considerable thickness.

Varieties are-a. Cannel Coal, a compact, semifissile coal; breaks with a semiconchoidal smooth fracture, with little or no lustre; colour dull black or greyish black.

Cannel Coal is bituminous and often caking. Of it Dana writes: "On distillation it affords, after drying, 40 to 66 of volatile matter, and the material volatilized includes a large proportion of burning and lubricating oils. It graduates into oil-producing coaly shales, the more compact of which it much resembles."

NOTE.-Some varieties of anthracyte have erroneously been classed as Cannel coal, on account of their smooth, close texture.

Subvarieties are-(a.) Parrot Coal, (b.) Horn Coal.

A Scotch subvariety is called Parrot Coal, because it burns with a crackling noise; while a Welsh is named Horn Coal, as it emits, when burning, an odour like that of burnt horn. An earthy subvariety is called, in Yorkshire, Clod.

most common repositories of aragonite are beds of gypsum, and beds of iron ore (where it occurs in coralloidal forms, and is denominated Flosferri), basalt, and igneous rocks."-Dana.

g. Manganese Ores, generally in the older rocks, but also in surface deposits.

h. Rhodochrosite occurs generally in veins, but at Glendree, Clare, Ireland, it forms part of the surface-deposits.

i. Bole, in subordinate masses, in limestone. j. Opal, or Vitryte, in very subordinate masses. k. Fluorite, and l. Barite, rarely found in beds or layers, often occur as gangue in mineral veins.

m. Ankerite, sometimes as an independent rock. n. Malachite, usually in veins.

o. Melanite, in small accumulations.

p. Galmey, or Calamine, as aggregates in dolomyte.

q. Zincite, r. Galenite, s. Stibnite, and t. Arsenopyrite, rarely occur as subordinate layers, but more generally in veins.

u. Sulphur, in concretions and layers, principally in marl and limestone, also in the vicinity of volcanoes.

v. Wavellite, in subordinate beds or layers. w. Chalcopyrite, usually in veins.

C. Rocks partly mechanically, partly chemically, and i

partly organically formed. These rocks are always more or less crystalline, and usually occur as subordinate beds, interstratified with sedimentary rocks, but not always.

A. LAMINATED or STRATIFIED COAL.-A more or less fissile crystalline aggregate of carbonaceous

matter; arenaceous or argillaceous to a greater or less degree!

Most coals do not belong to the Subaqueous rocks; some, however, have been formed mechanically from carbonaceous matter, that was first denuded, and afterwards deposited in the sea, or other waters.

NOTE. At the present day the accumulation of mechanicallyformed coal can be observed. Wherever peat-bogs or even hard coal-beds are exposed to denudation, more especially to marine abrasion, they are gradually carried away to be deposited in seas, lakes, &c., forming stratified more or less arenaceous or argillaceous carbonaceous beds, which eventually must be indurated, forming a hard coal. Some of these deposits in the vicinity of the Irish coast are of considerable thickness.

Varieties are-a. Cannel Coal, a compact, semifissile coal; breaks with a semiconchoidal smooth fracture, with little or no lustre ; colour dull black or greyish black.

Cannel Coal is bituminous and often caking. Of it Dana writes: "On distillation it affords, after drying, 40 to 66 of volatile matter, and the material volatilized includes a large proportion of burning and lubricating oils. It graduates into oil-producing coaly shales, the more compact of which it much resembles."

NOTE. Some varieties of anthracyte have erroneously been classed as Cannel coal, on account of their smooth, close texture.

Subvarieties are—(a.) Parrot Coal, (b.) Horn Coal.

A Scotch subvariety is called Parrot Coal, because it burns with a crackling noise; while a Welsh is named Horn Coal, as it emits, when burning, an odour like that of burnt horn. An earthy subvariety is called, in Yorkshire, Clod.