ANY
interesting facts about precious stones do not properly refer either to
their talismanic or curative powers, and yet serve in not a few cases
to indicate more or less clearly the reasons which have determined
popular fancy or superstition in attributing particular virtues to a
given stone.
As
an instance of the strange vagaries of belief in the influence exerted
by certain of these stones, we may take the statement that powdered
agate dissolved in beer was used by the Bretons as a test of virginity.
If a young girl were unable to retain this delectable mixture on her
stomach, she was supposed to be impure.1 The ability to stand this test seems rather to prove the possession of a strong stomach than a clear conscience.
Rainbow
Agate is a name appropriately applied to agates showing a beautiful
prismatic effect. These are composed of quartz and chalcedony in very
fine layers. The writer secured a splendid specimen of this type of
agate set in a jewel which had formed part of an old Saxon collection;
it may possibly have come from India. The prismatic play of color
differs from that observed in quartz iris, in that the iridescence is
due to the minute interference lines and not, as with the iris, to
internal fractures.
The
greatest interest was manifested in the eighteenth century in these
agates, one of which was described in a special pamphlet under the
title, "Regenbogen Achat," and
1 Wilhelmus Parisiensis, quoted in Fancirollus, " History of Many Memorable Things," London, 1715, vol. i, p. 42.
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