(heliotropium), among the ancients, an instrument or machine for showing when the sun arrived at the tropics and the equinoctial line. This name was also used for a fun-dial in general.

Heliotrope is also a precious stone, of a green colour, streaked with red veins. Pliny says it is thus called, because, when cast into a vessel of water, the sun's rays falling thereon seem to be of a blood-colour; and that, when out of the water, it gives a faint reflection of the figure of the sun; and is proper to observe eclipses of the sun as a helioscope. The heliotrope is also called oriental jasper, on account of its ruddy spots. It is found in the East Indies, as also in Ethiopia, Germany, Bohemia, &c. Some have attributed to it the faculty of rendering people invincible, like Gyges's ring.