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The iron oxide concretions found in the Navajo Sandstone exhibit a wide variety of sizes and shapes. Their shape ranges from spheres to discs; buttons; spiked balls; cylindrical hollow pipe-like forms; and other odd shapes ... many more also occur as isolated concretions, which range in diameter from the size of peas to baseballs. The surface of these spherical concretions can range from being very rough to quite smooth.
Navajo "Pipes"... They range in size from less than 1 cm to greater than 50 cm in diameter and their walls are as much as 1 cm thick. They extend through the Navajo Sandstone for more than several meters. They are regarded as having formed as the result of the dissolution of siderite cements and the redistribution and oxidization of the released iron by groundwater flow. Hematite also occurs as other masses of diagenetic "ironstone" that exhibit a wide and amazing range of bizarre shapes, which can be described as both "strangely shaped stones" and "rusty scraps". Strangely shaped stones, pipe-like features, and other concretionary masses have been observed and described from the Navajo and other Jurassic sandstones in Utah and adjacent American states.The reported composition of the rusty scraps, 30 percent ferric oxide and large amounts of silicon dioxide and calcium oxide, is consistent with the hematite masses found in the Navajo and other Jurassic sandstones in Utah and elsewhere in the Southwestern United States. The ferric oxide and large amounts of silicon dioxide is what a person would expect iron oxide cemented sandstone to consist of. Calcite and other carbonate cements and concretions are typically associated with the hematite masses in the Navajo and other sandstones and sedimentary rocks
To RD:thanks for the info on Navajo pipes, i do certainly see the resemblance but this specimen is definitely solid.
Started by Headmole