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sheets
of chalcedony, varying in thickness from that of thin paper to nearly
an inch. These chalcedony veins ramify in all directions, and often
extend for many rods without interruption.
When
the chalcedony is penetrated by branching forms of manganese or iron
oxide, the forms known as "mocha stones" and "moss-agates" are
produced. These are not due to vegetation, any more than the similar
forms of frost on our window-panes. Moss-agates are found in numerous
localities in the States of Utah, Wyoming, Colorado, and Montana. Kunz
remarks that "no stone that is used in jewelry in the United States is
cheaper, more beautiful, or more plentiful than the moss-agate." The
best occur as rolled pebbles in the beds of streams. The name "mocha
stone," sometimes applied to moss-agates, is either due to the fact
that those first used came from Mocha in Arabia, or it is a corruption
of the word moss-agate. The finest moss-agates now known come from
India. A white variety of chalcedony, containing minute blood-red
spots, is known as St. Stephen's stone. Chalcedony was formerly used
much more and more highly prized than at the present time. It was
especially employed for seals and rings, but also for plates, cups, and
vases. These were often engraved in the most elaborate manner, the
hardness and toughness of £he stone being well suited to this purpose.
The sentiment of the stone is: "A disperser of melancholy." The name
chalcedony is from Chalcedon, a city in Asia Minor, where the original
chalcedony was found. This mineral was probably not like our modern
chalcedony, but a green quartz. This chalcedony is mentioned in the
Book of Revelations as one of the foundation stones of the Holy City.
Carnelian is
a red variety of chalcedony; sard a brown variety. All gradations
between these shades of course occur, those of the reddish cast being
the most common. The most highly prized color for carnelian is a deep
blood-red, appearing darker red in reflected
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