Agate
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Agate is a banded variety of fibrous chalcedony. Agate stones are characterized by alternating bands of different colored chalcedony and often contain some visible quartz crystals. They are common in
Polished agate nodule from Malawi
When backlit, thin slices of agate can occasionally show their fibrous structure as lines running perpendicular to the bands (top)
Agate exhibiting wall banding (top) and level banding (bottom)
Agate geode slice with macrocrystalline quartz and a hollow center
Moss agate
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Moss agate is a semi-precious gemstone formed from silicon dioxide. It is a form of chalcedony which includes minerals of a green color embedded in the stone, forming filaments and other patterns sugg
Agate
…concentrically banded, while some have bands that form parallel lines. Certain varieties of chalcedony without bands are commonly called agate (e.g. moss agate, fire agate), but these are not true agates. Moreover, not every banded chalcedony is an agate (e.g. banded chert). Most agates form as nodules within…
Moss agate pebble, 1 inch (25 mm) long
Montana moss agate
Gothic-Style Bracelet; gold, carnelian, malachite, moss agate, amethysts, aquamarines, rubies. The Walters Art Museum.