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Agate banded 750pix.jpg
Bandit agate (agate-lik onyx); the specimen is 2.5 cm (1 inch) wide
Category Quartz variety
(repeatin unit)
SiO2 silicon dioxide
Creestal seestem Rhombohedral Microcrystalline
Colour White tae grey, licht blue, orange tae reid, black. bandit
Creestal habit Cryptocrystalline silica
Cleavage None
Fractur Conchoidal wi very sharp edges.
Mohs scale haurdness 6.5–7
Skinkle Waxy
Streak White
Diaphaneity Translucent
Speceefic gravity 2.58–2.64
Refractive index 1.530–1.540
Birefringence up to +0.004 (B-G)
Pleochroism Absent

Agate /ˈæɡət/ is a microcrystalline variety o silica, chiefly chalcedony, characterised bi its fineness o grain an brichtness o colour. Altho agates mey be foond in various kinds o rock, thay are classically associatit wi volcanic rocks an can be common in certain metamorphic rocks.[1]

References[eedit | eedit soorce]

  1. Donald W. Hyndman, David D. Alt (2002). Roadside Geology of Oregon (18th ed.). Missoula, Montana: Mountain Press Publishing Company. p. 286. ISBN 0-87842-063-0.