• Title/Summary/Keyword: minerals likely to contain asbestos

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Asbestos Analysis and Mineralogical Characterization for Commercial Products Containing Talc, Vermiculite, Sepiolite, and Serpentine (활석, 질석, 해포석, 사문석 등 석면함유 가능성이 있는 광물 함유 제품의 석면 분석 및 광물학적 특성)

  • Yeonju Choi;Yumi Kim;Chaewon Kim;Yul Roh
    • Economic and Environmental Geology
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    • v.57 no.5
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    • pp.563-575
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    • 2024
  • In Korea, talc, vermiculite, sepiolite, and serpentine were designated as minerals likely to contain asbestos (MLCA) according to the Ministry of Environment (Asbestos Safety Management Act). The asbestos content in commercial products made of MLCA must not exceed 0.1 %. In this study, mineralogical analyses using PLM, XRD, and TEM-EDS were used to characterize the presence, content, and morphological characteristics of asbestos in MLCA-containing commercial products. A total of 28 samples were analyzed, including 18 cosmetics containing talc, 5 fertilizers containing vermiculite, 2 pet sanitary products containing sepiolite, and 3 accessories containing serpentine. All samples were heated at 450 ℃ for 6 hours to remove organic matter prior to XRD and PLM analyses according to the Ministry of Environment guidelines. Additionally, the presence and morphology of elongated mineral particles (EMPs) were investigated using TEM-EDS analysis according to the recently revised asbestos analysis method (FDA-2020-N-0025) by the US FDA. The analyses showed that no asbestos was detected in both talc-containing cosmetics and sepiolite-containing products, but actinolite asbestos was found (<0.25 %) in vermiculite-containing fertilizers and chrysotile was found (<0.25 %) in decorative serpentine stones. In TEM-EDS analysis, multiple columnar/fibrous particles measuring 0.5 ㎛ or more in length were observed in talc-containing products, and short chrysotile fibers were observed in bracelets containing serpentine. Therefore, these results indicated that the MLCA-containing products that come into direct contact with the human body would require management through precise inspection and continuous monitoring considering EMPs of 5 ㎛ or less. Furthermore, TEM-EDS for asbestos analysis indicated that it could overcome the detection limits of XRD and PLM analyses for short or thin asbestos fibers, thereby improving the precision and accuracy of asbestos analysis.

Interpretation of the Manufacturing Characteristics and the Mineral and Chemical Composition of Neolithic Pottery Excavated from the Jungsandong Site, Yeongjong Island, South Korea (영종도 중산동 신석기시대 토기의 광물 및 화학조성과 제작특성 해석)

  • Lee, Chan Hee;Kim, Ran Hee;Shin, Sook Chung
    • Korean Journal of Heritage: History & Science
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    • v.51 no.1
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    • pp.4-31
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    • 2018
  • The Neolithic pottery excavated from the Jungsandong site has been classified into four types of pottery (I: feldspar type, II: mica type, III: talc type and IV: asbestos type) according to their mineral composition. These four types of potteries generally appear to have undergone incomplete firing, while the level of oxidation in the type I pottery objects, which have a relatively higher clay content, was found to be particularly low. The type III objects, which have a high talc content, are judged to have been somewhat slow in removing carbon because they contain saponite belonging to the smectite group. Of the four types of pottery, type IV showed the highest redness and the most uniform characteristics, thus indicating a good level of oxidation. In particular, fixed carbide (C; 33.7 wt.%) with a thickness of about 1mm, and originating from organic substances, was detected inside the walls of the type I pottery, while the deep radial cracks in the outer surfaces of the pottery are thought to have been caused by repeated thermal shocks. Given that all of the pottery except for the type I artifacts are considered to be have been made for storage purposes, those containing talc and tremolite are easy to done liquid storing vessels based on an analysis of their material characteristics. As for the type II relics, which are composed of various minerals and exhibit poor physical properties, they seem to have been used for simple storage purposes. As domestic talc and asbestos mines were concentrated in the areas of Gyeonggi, Gangwon, Chungbuk, and Chungnam, it seems likely that talc and tremolite were produced as contiguous minerals. Considering the distance between the remains in Jungsandong and these mines and their geographical distribution, there is a possibility - albeit somewhat slight - that these mines were developed for the mining of various minerals. Although ultramafic rock masses - such as serpentine capable of generating talc and tremolite - have not been found in the Jungsandong area, limestone and biotite granite containing mica schist have been identified in the northwestern part of Yeongjong Island, indicating that small rock masses might have formed there in the past. Therefore, it is judged necessary to accumulate data on pottery containing talc and tremolite, other than the remains in Jungsandong, and to investigate the rocks and soils in the surrounding area with greater precision. The firing temperatures of the pottery found at the Jungsandong site were interpreted by analyzing the stability ranges of the mineral composition of each type. As a result, they have been estimated to range from 550 to $800^{\circ}C$ for the type I artifacts, and from 550 to $700^{\circ}C$ for the type I, II and IV artifacts. However, these temperatures are not the only factors to have affected their physical properties and firing temperature, and the types, particle sizes, and firing time of the clay should all be taken into consideration.