"Meteoric stones exemplify the same chemical and crystallographic
laws as the rocks of the earth, and have afforded no new element or
principle of any kind."[2]

It may be presumed, therefore, that the granite crust of the exploded
globe from which some comet was created was the source of the finely
triturated material which we know as clay.

But the clays are of different colors--white, yellow, red, and blue.

[1. "Popular Science Monthly," November, 1881, p. 86.

2. "Manual of Geology," p. 3.]

{p. 75}

"The aluminous minerals contained in granite rocks are feldspar,
mica, and hornblende. . . . Mica and hornblende generally contain
considerable oxide of iron, while feldspar usually yields only a
trace or none. Therefore clays which are derived from feldspar are
light-colored or white, while those partially made up of decomposed
mica or hornblende are dark, either bluish or red."[1]

The tail of the comet seems to be perpetually in motion. It is, says
one writer, "continually _changing and fluctuating_ as vaporous
masses of cloud-like structure might be conceived to do, and in some
instances there has been a strong appearance even of an _undulating
movement_."[2]