A Mixture Of:Moganite, Quartz

Traditionally defined as a fibrous cryptocrystalline variety of Quartz, more recently, it has been shown that much Chalcedony is a mixture of Quartz and Moganite, another Silica mineral.

When it is concentrically banded (often in rather wild patterns) it is called by the subvariety name agate. When it is in flat layers/bands it is called by the subvariety name onyx.

[Note: Many non-banded forms of chalcedony - such as moss agate - are often erroneously called 'agates'. True agate is concentrically banded. Mottled and included chalcedonies are more properly called simply 'chalcedony.' Agatized wood is the name given to fossil wood where the replacement of the wood is by chalcedony, but the banding in this case is due to the wood structure - not concentric deposition of the chalcedony - and the material is chalcedony, not true agate.]

Classification of Chalcedony URL:
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Physical Properties of Chalcedony

Hardness (Mohs'):7

Relationship of Chalcedony to other Species

Common Associates:

Other Names for Chalcedony

  • Gelite (in part)
  • Varieties:
    Abakusz-köAgateAgate-JasperAmarillo StoneAmberine
    AzurchalcedonyBinghamiteBloodstoneBlue Lace AgateBotswana Agate
    Brecciated AgateBuhrstoneCarnelianCloud AgateCrazy Lace Agate
    CubosiliciteDamsoniteDendritic AgateEnhydro AgateEye Agate
    Fairburn AgateFire AgateFortification AgateFossil AgateHaema-ovoid-agates
    Iris AgateKeystonite ChalcedonyLaguna AgateLake Superior AgateLandscape Agate
    Mexican Lace AgateMoss AgateMtoroditeMyrickiteNipomo Agate
    OnyxPetrified WoodPigeon Blood AgatePlume AgateQuartzine
    Riband AgateSardSardonyxSeftoniteTigers Eye

    Other Information

    Health Warning:There is no specific data on health dangers or toxicity for this mineral, however you should always treat mineral samples as potentially toxic/dangerous and use sensible precautions when handling them.

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