One side of this matrix is covered by lustrous octahedral black crystals of magnetite measuring to 2.0 cm in size. In good condition.Twin Peaks in Millard County, Utah, features a bimodal volcanic field characterized by Miocene to Pleistocene rhyolite domes and basalt flows where fissure-filling iron mineralization occurs along fault zones. Small-scale historical mining operations extracted limited amounts of iron ore from narrow veins containing high-grade iron oxides, including notable deposits of magnetite. Mineral collectors have long valued the locality for producing sharp, well-formed octahedral crystals of metallic magnetite that often occur within the volcanic host rock or loose surface materials, making it a classic western American mineral occurrence.
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