Carnelian, sometimes spelled cornelian, is a red or reddish-brown variant of chalcedony. Similar to carnelian is sard, which is generally harder and darker. Chalcedony knife, AD 1000-1200 Bloodstone redirects here. ... A chemical formula is an easy way of expressing information about the atoms that constitute a particular chemical compound. ... The chemical compound silicon dioxide, also known as silica, is the oxide of silicon, chemical formula SiO2. ... The molecular mass of a substance (less accurately called molecular weight and abbreviated as MW) is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon-12). ... A crystal system is a category of space groups, which characterize symmetry of structures in three dimensions with translational symmetry in three directions, having a discrete class of point groups. ... Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite planes, creating smooth surfaces, of which there are several named types: Basal cleavage: cleavage parallel to the base of a crystal, or to the plane of the lateral axes. ... Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer. ... Lustre (American English: luster) is a description of the way light interacts with the surface of a crystal, rock or mineral. ... The streak (also called powder color) of a mineral is the color of the powder produced when it is dragged across a unweathered surface. ... Relative density (also known as specific gravity) is a measure of the density of a material. ... Chalcedony knife, AD 1000-1200 Bloodstone redirects here. ... Sard is a reddish-brown chalcedony, SiO2, much used by the ancients as a gemstone. ...

Distinction between carnelian and sard

The words carnelian and sard are often used interchangeably, but they can also be used to describe distinct subvarieties. The purported differences are as follows:

It should be noted that all of these properties vary across a continuum, and so the boundary between carnelian and sard is inevitably blurred.

History

Carnelian intaglio with a Ptolemaic queen, Hellenistic artwork, Cabinet des Médailles

Carnelian was used widely during Roman times 2,000 years before the present era to make signet or seal rings for imprinting a seal with wax on correspondence or other important documents. Hot wax does not stick to Carnelian. ^[2] Intaglio is a printmaking technique in which the image is incised into a surface. ... Ptolemy, one of Alexander the Greats generals, was appointed satrap of Egypt after Alexanders death in 323 BC. In 305 BC he declared himself King Ptolemy I, later known as Soter (saviour). ... Gold 20-stater of Eucratides I (175-150 BCE), the largest gold coin ever minted in Antiquity. ...

The word carnelian is derived from the Latin word meaning horn, in reference to the flesh color sometimes exhibited. For other uses, see Latins and Latin (disambiguation). ...

Folklore

Carnelian is the zodiac birthstone of Virgo according to some texts. It is also one of the gemstones (along with peridot, diamond and sapphire) that has been associated with the month August. This article is about the mineral. ... As a gemstone, diamond is perhaps the most valued. ... For other uses, see Sapphire (disambiguation). ...

See also

• Carnelian beads
• List of minerals

Carnelian beads (other variants of the name include Cornelian beads, sadoine, Mecca stone, and pigeon’s blood agate) are a gemstone jewelry made of carnelian quartz. ... Gem animals. ...

References

1. ^ Rudolf Duda and Lubos Rejl: Minerals of the World (Arch Cape Press, 1990)
2. ^ Section 12 of the translation of Weilue - a 3rd century Chinese text by John Hill under "carnelian" and note 12.12 (17)

External links

• Mindat article on carnelian