Carnelian
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Carnelian is a brownish-red mineral commonly used as a semiprecious stone. Similar to carnelian is sard, which is generally harder and darker; the difference is not rigidly defined, and the two names
Carnelian sard
Carnelian intaglio with a Ptolemaic queen, Hellenistic artwork, Cabinet des Médailles, BnF Museum, Paris
Chalcedony
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Chalcedony is an aggregate of cryptocrystalline or microcrystalline silica, or in simpler terms, a mass of individual silica crystals that are too small to be seen without magnification. It is compose
Carnelian
…the difference is not rigidly defined, and the two names are often used interchangeably. Both carnelian and sard are varieties of the silica mineral chalcedony colored by impurities of iron oxide. The color can vary greatly, ranging from pale orange to an intense almost-black coloration. Significant localities…
A botryoidal geode specimen from Chihuahua
A rare pseudomorph of a spiral Turritella-like snail shell that has been replaced by chalcedony
Chalcedony mouse, by Avenir Sumin
Agate