agate (mocha stone) Variety of chalcedonic silica (SiO₂) that is cryptocrystalline. It is similar to chalcedony except that impurities of iron and manganese may give it a distinct colour banding which is frequently precipitated in concentric zones. Moss agate contains delicate, fern-like, dendritic patterns. Agates may be cut and polished as decorative stones.

ag·ate / ˈagit/ • n. an ornamental stone consisting of a hard variety of chalcedony, typically banded in appearance. ∎  a colored toy marble resembling a banded gemstone.

Agate (or Achates)

According to ancient tradition, this precious stone protected against the biting of scorpions or serpents, soothed the mind, drove away contagion, and put a stop to thunder and lightning. It was also said to dispose the wearer to solitude, promote eloquence, and secure the favor of princes. It gave victory over enemies to those who wore it.

agate Microscrystalline form of quartz with parallel bands of colour. It is regarded as a semi-precious stone and is used for making jewellery. Hardness c.6.5; r.d. c.2.6.

agate variety of chalcedony. XVI. — (O)F. — L. achātēs — Gr. akhā́tēs.