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1
by Keller, P.C.
Published 1990
Springer US
Table of Contents: “... Waters: The Gem Gravels of Sri Lanka -- 2. Gemstones Formed from Surface Water: The Opals of Australia...”
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2
by Pohl, Walter L.
Published 2011
Wiley Blackwell
Table of Contents: “... -- Metamorphic quartzite deposits -- Sedimentary quartzite -- Quartz sand and gravel -- Industrial sand...”