Glistening spray of needlelike natrolite crystals 1.5 cm in diameter set nicely up on a basalt matrix. Collected in the very early 1980s. In good condition. The specimen comes with a previous collection label from Ray DeMark.The geology around Horseshoe Dam along the Verde River in Maricopa County, Arizona consists primarily of rugged Precambrian basement granites and schists overlain by complex mid-Tertiary volcanic and sedimentary rock sequences, including basaltic, dacitic, and rhyolitic flows. While the area is best known historically for the construction of the earth and rockfill dam by Phelps Dodge during World War II to secure water and power supplies for regional copper mining and agriculture, the surrounding desert terrain features localized mineral occurrences.
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