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Heliotropium, Heliotrope

Agates, Jet Page of 453 Heliotropium, Heliotrope Text size:minus plus Restore normal size   Mail page  Print this page
       
     
 
HELIOTROPIUM.
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HELIOTROPIUM: Heliotrope.
This stone retains its ancient name, and is a Prase, or semi-transparent, green Calcedony, interspersed with small patches of opaque, bright red Jasper. It is Pliny's variety of the Prasius, which " sanguineis punctis obhorret." India then, as now, furnished this beautiful stone, the best specimens of which present a pleasing combination of an emerald green nearly trans­parent, and of the most vivid red.
This must be distinguished from the Bloodstone, often impro­perly called Heliotrope, the latter being a green Jasper, perfectly opaque as to both its constituent colours, and a much commoner material, found also in many parts of Europe.
The origin of the name (Sun-turner) is thus given by Pliny (60) : " The Heliotrope produced in Ethiopia, Africa, and Cyprus, is of the colour of the leek (as the Prasius), and marked with veins of blood. The reason of its name is, because, if thrown into a pot of water, it (especially the Ethiopian kind) transforms the sun's light falling upon it into the reflection, as it were, of blood (sanguineo repercussu). The same stone, out of the water, acts as a mirror for observing and detecting solar eclipses, and showing the moon passing over his disk."
This last notice is very curious, referring as it does to the method resorted to by the old astronomers for making solar observations ; for, it must be borne in mind that the chief authorities upon the properties of Gems, quoted by Pliny in his alphabetical list, were the Magi, the fathers of astronomy. It is difficult, however, to conceive how a tablet of Heliotrope could be used as a mirror ; but, on the other hand, a thin slice of a green transparent stone would admirably protect the eye of an observer looking through it. Perhaps here, as in the case of Nero's emerald, there may be a confusion of the two ideas, between the looking into a reflector, and the looking through a transparent medium.
  
 
 
  
       
Agates, Jet Page of 453 Heliotropium, Heliotrope
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