chalcedony

agate

Agate is a variety of chalcedony characterized by either transparency or color patterns, such as multi-colored curved or angular banding. Opaque varieties are sometimes referred to as jasper.

history

In the Bronze Age chalcedony was in use in the Mediterranean region; for example, on Minoan Crete at the Palace of Knossos, chalcedony seals have been recovered dating to circa 1800 BC.

random

Eta Geminorum (Wikipedia) Eta Geminorum (η Geminorum, abbreviated Eta Gem, η Gem), formally named Propus /ˈproʊpəs/, is a triple star system in the constellation of Gemini. It is a naked-eye variable star around 380 light years from the Sun.

tags

variety

Wikidata

https://www.wikidata.org/wiki/Q170448

Wikipedia

Chalcedony (Wikipedia) Chalcedony (/kælˈsɛdəni/ kal-SED-ə-nee, or /ˈkælsəˌdoʊni/ KAL-sə-doh-nee) is a cryptocrystalline form of silica, composed of very fine intergrowths of quartz and moganite. These are both silica minerals, but they differ in that quartz has a trigonal crystal structure, while moganite is monoclinic. Chalcedony’s standard chemical structure (based on the chemical structure of quartz) is SiO2 (silicon dioxide).