The Khur Agate Field
Khur agate field, Khur-e-Biabanak, Esfahan province
The Khur agate and geode field is located approximately 25km southeast of the Khur city, in northeast Naieen, between Tehran and Yazd. The Khur agate field in Central Iran with its fine blue agates, is my favorite agate field in Iran.
The agate and geode nodules are formed in the gas vesiculs of altered andesitic lavas which embeded in a thick altered tuff layer with lower to middle Eocene in age. This tuffaceous layer in some places altered to montmorillonite (bentonite) completely. In this localities agates and geodes find as loose
nodules on the surface. This agate field is located adjacent a bentonite clay mine which is now abandon.
General landscape of the khur agate field includes altered tuff with white to red color, that hosts nodules is located in downslope of the mounds and covered by a brown andesite lava layer. It looks like "Badland" feature at first sight. This agate field is located in the southern boarder of "Great Kavir" which is a vast salt playa in Central Iran.
Location of the Khur area in Central Iran
General landscape of the Khur agate field
Natural distribution of loose nodules of agate and geode on the surface of the altered (bentonitized) tuffs.
Relation between 2 geode nodules and hydrothermal veins. Nodules with green celadonite crust are rare in Khur.
Offseting and re-joining in an agate nodule due to faulting. 66x32 mm
Blue agate nodule with a few collapsed "crust" fragments inward. 65x44 mm
Light blue agate. 58x53 mm
Pale blue "Flame agate". 47x37 mm
Blue agate with central geode. 27x28 mm
Agate & colloform banded crust. 29x23 mm
Agate with thick carbonate crust. 52x47 mm
White "Porcelain Agate". 30x 38 mm
Agate with red layers and stalactitic stractures in center. 31x25 mm
Blue agate with collapsed structure of brown outer crust layer. 40x33 mm
Sagenitic Agate. Growth of radiated crystals of aragonite on the crust. 32x17 mm
Aragonite bands replaced by manganese oxides. 44x36 mm
"Plume agate". 64x53 mm
Aragonite sprays in clear agate.54x35 mm
Pseudo-hexagonal crystals of aragonite replaced by chalcedony & quartz. 62x42 mm
"Moss agate". Growth of Mn oxide minerals with dendritic aggregate in agate. 41x38 mm
Dendritic agate with "White Pine" like center filled quartz. 60x44 mm
Geode of quartz with quartz crystals lining and calcite crystals overgrow. 52x42 mm
Quatrz geode with growth of large calcite and fine Mn-oxide sprays on them. 35x32 mm
Pre-banding inclusions of calcite crystals. Side edge represents 20 mm.
Celestite crystal growing in a geode. Side edge represents 8 mm.
Post-banding inclusion of calcite crystals. Side edge represents 8 mm
Coloform aggregate of auricacite around the base of celestite crystal, in a geode. Side edge is 4 mm.
Growth of rhombohedral siderite crystals on quartz crystals of a geode. Side edge represents 4 mm.
SEM image of flat needles of goethite on quartz crystals in a geode.
SEM image of goethite crystals showing feather-like aggregate.
