Mineralogy and gemological characteristics of agates from Kasrab and Bahamarz regions (Southeast of Sarbisheh, South Khorasan Province)

Document Type : Original Article

Authors

University of Tabriz

10.22128/ijcm.2025.2971.0

Abstract

The study area is located in the Kasrab-Bahamarz region, 45 km southeast of Sarbisheh, and in terms of structural zone, it is located in the flysch zone of eastern Iran. In this region, mineralization of agate and jasper gemstones has occurred in vein-vein form within Paleocene volcanic units such as pyroclastic rocks (tuffs). Based on XRD analysis, the pore-filling compounds are mainly cryptocrystalline quartz and to a lesser extent dolomite. Based on microscopic examination, the minerals that make up these agates are jasper and chalcedony. Veined and cauliflower textures are the most important textures seen in hand-cut agate samples from this region. Agates and jaspers from this region are found in blue, green, red, purple, orange, white, and black colors, with a specific gravity of 2.57 to 2.62, a refractive index of 1.52 to 1.56, they have good polishability, are translucent to opaque, and lack fluorescence and multicolor properties. The most important factor in creating the color of green agates is the elements chromium and nickel, while in blue agates it is the element copper, in red, orange and black agate jasper, the elements iron and manganese, and also in purple agates, there are elements of manganese and copper. The lack of color-forming elements in white jaspers has caused the neutral color in this sample.

Keywords

References

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Iranian Journal of Crystallography and Mineralogy
Volume 33, Issue 4 - Serial Number 100
January 2026
Pages 667-680

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History

  • Receive Date: 18 March 2025
  • Revise Date: 07 April 2025
  • Accept Date: 07 May 2025

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