At the Monroeville locality, barite has a unique morphology, which often causes the crystals to have a mix of vitreous and crude faces. Discounting the fact that some crystals of barite have been heavily corroded from exposure to the elements of the river, many of the fresher crystals on the inside of septaria have certain naturally rough faces. These rough, rounded, etched or feathered faces make the task of identifying additional modifications nearly impossible. A very few sporadic crystals without distorted faces have also been observed but are not as common. The crude faces are generally an indication of the rate at which the crystalsRead More →

While the Diploidal form with trapezohedral modifications is the most common crystal form observed at the Duff Quarry, it is not exclusive. In a study of diploidal forms conducted for this article, the forms A-H represent one observable progression of crystal modifications. Other progressions of this type can and do exist. Additional modifications are possible, however no diploidal crystals with expanded form beyond form H were discovered in this study. Crystals with modifications of unequal size are common. For example, a diploidal crystal with octahedral modifications should have 8 equal sized symmetrical octahedral faces. However, one diploidal pyrite crystal with octahedral modifications may have 8Read More →

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