Name/Title
Onyx Stone EggEntry/Object ID
2004.5.23Description
Chemical Composition: Sio2 Silicon Dioxide
Description: pink with black and white spots 3 inches long
Onyx is a cryptocrystalline form of quartz. The colors of its bands range from white to almost every color (save some shades, such as purple or blue). Commonly, specimens of onyx available contain bands of colors of white, tan, and brown. Sardonyx is a variant in which the colored bands are sard (shades of red) rather than black. Pure black onyx is common, and perhaps the most famous variety, but not as common as onyx with banded colors.
It has a long history of use for hardstone carving and jewellery, where it is usually cut as a cabochon, or into beads, and is also used for intaglio or cameo engraved gems, where the bands make the image contrast with the ground. Some onyx is natural but much is produced by the staining of agate.
The name has sometimes been used, incorrectly, to label other banded lapidary materials, such as banded calcite found in Mexico, Pakistan, and other places, and often carved, polished and sold. This material is much softer than true onyx, and much more readily available. The majority of carved items sold as 'onyx' today are this carbonate material.[1]
Rock Origin: Post-depositional
Rock Type: IgneousCollection
Suomynona Mineral CollectionAcquisition
Accession
2004.5Source or Donor
Suomynona Egg CollectionAcquisition Method
DonationLocation
Location
Shelf
CS-I-7Room
Curation StorageBuilding
Crater Rock MuseumCategory
StorageMoved By
Jillian Mather KettleyDate
May 1, 2025Category
PermanentMoved By
Scott LonganDate
October 29, 2009