parallel.
If the stripes run together around the centre, it is called the circle
agate, and if in the same stone the centre shows more colored spots, it
is called the eye agate, or eyestone.
2d.
Fortification agate is that brownish agate, the various colored
stripes of which run in a zig-zag, or irregular lines and angles,
representing the ground plan of fortifications.
3d.
Rainbow agate ; the curved stripes have the property of displaying
rainbow colors when held towards the sun, or candle-light, and the more
distinctly if the stone is cut very thin.
4th.
The cloud, landscape, dendritic, figure, moss, punctated, star,
petrifaction, shell, coral, tube, fragment, and ruin agates are all the
various forms in which the agate is displayed, according to its figure
or drawing. A ruin or fragment agate may be pasted together from the
fragments of a common ribbon agate, so as to make it represent old
walls, whereby it receives the name of breccia agate ; sometimes the
rainbow agate occurs in connection with the "shell agate", where the moss
surrounding the petrified shells forms the rainbow agate.
The
royal collection at Dresden contains a table service of German agate :
at Vienna, in the imperial cabinet, there is an oval dish twenty-two
inches in length, formed from a single stone.
The
achates of the Greeks were so called from the river Achates, in Sicily,
whence, according .to Theophrastus, these stones were originally
brought.
Jaspachates corresponds to our jasper agate ; sardachates contained layers of the sarda, or carnelian ; dendrachtes, from
a tree, corresponding to our moss agate ;
haemachates, from
blood, which was an agate sprinkled,
with spots of red jasper.
