• Korean Journal of Mineralogy and Petrology
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• v.36 no.4
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• pp.233-257
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• 2023

Asbestos minerals are found at rocks and soils of the Hongseong and Bibong serpentine mines, western part of Chungnam. The area consists of and metasediment, and Mesozoic igneous intrusives with minor age-known gneiss complexes and Mesozoic sediments. With detailed geological investigations, rock samples for the serpentinite and amphibolite areas are collected at sites containing asbestos. Representative asbestos and rock samples are analysed by PLM, XRD, SEM and EPMA. Serpentinites are found as steeply dipping faults with adjacent gneiss complex to the NNE direction. Repeated alteration, including serpenitization and talcification, is found at the emplacement direction for the serpentinite body. Amphibollites occur as intrusives and stratiforms within the Precambrian gneiss complex. Serpentinite and amphibolite (or amphibole schist) contain amphiboles either as asbestiform or non-asbestiform. Varying amounts of asbestos minerals, including chrysotile, tremolite asbestos and actinolite asbestos, are found within the serpentinites. The asbestos minerals are found near the cracks or fractures and along the bedding plane. They occur as cross fiber, slip fiber and mass fiber types. Varying amounts of amphibole asbestos minerals, such as tremolite and actinolite asbestos, are found within amphibolites and as a mass fiber type. Overall results suggest that rocks of the serpentine mines contain serpentine and amphibole type asbestos minerals originated from the hydrothermal alteration. Considering construction nearby the mines and environmental risks by the asbestos, additional land management plans are required.

• Economic and Environmental Geology
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• v.47 no.5
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• pp.489-496
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• 2014

The occurrence and mineralogical characteristics of asbestos in dolostone at Ungdo, Seosan were investigated by analyses of PLM, XRD, and SEM/EDS. Representative outcrops of dolostone at Ungdo were examined and four dolostone samples were collected according the occurrence type to identify the shape of asbestos in dolostone samples. The host rock of dolostone had been produced from the hydrothermal alteration and/or thermal metamorphism of which main source was assumed as the acidic granite. Tremolites were observed near the cracks or fractures of the dolostone as tamping or gob types. From the mineralogical analyses, main minerals of dolostone were dolomite with calcite, quartz, talc, amphibole, and pyroxene. From SEM/EDS analyses, tremolite-actinolite asbestoses were observed in dolostone and their shapes were prismatic and fibrous (less than $1{\mu}m$ in width). Non-asbestos prismatic forms were also found and they would transfer to asbestos particles resulting from the cleavage and fracture of the prismatic particles. Overall results suggest that asbestoses in Ungdo dolosotnes were mainly tremolite-actinolite and they were originated from the hydrothermal alteration of Ca-Mg rich dolostone.

• Journal of the Mineralogical Society of Korea
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• v.32 no.1
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• pp.15-39
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• 2019

An ultramafic complex occurs as an isolated lenticular body in the Andong area. The Andong ultramafic complex comprises ultramafic and mafic rocks, but mainly peridotites. The complex extends for several kilometer to ENE direction, adjacent to the Andong fault line. This study is for petrochemistry of the peridotites within the ultramafic complex and characteristics of asbestos occurrences. The peridotites are igneous origin, ranging from lherzolite to wehrlites and are characterized by high Fo olivine ($Fo_{0.85-0.87}$), Mg clinopyroxene ($Mg_{87.5-93.5}$), and tremolitic to tschermakitic hornblende. Geochemically, these rocks show high magnesium number (mainly Mg = 85.3-87.38) and transitional element and low alkali element contents. The peridotites host asbestos, including chrysotile, tremolite and actinolite asbestos, but dominated by amphibole asbestos. The amphibole asbestos are found along small fault face, and cleavage and fracture showing several cm to ten cm in width as slip and oblique fibers, while the chryostiles occur at cleavage and vein showing several mm-cm in width as cross and slip fibers. They are confirmed by PLM, XRD and SEM results. Overall characteristics of peridotites from the Andong ultramafic complex and occurrences of the asbestos are similar to those of worldwide orogenic related Alpine type ultramafic rocks and serpentinized ultramafic bodies in Chungnam, Korea, respectively.