Genetic Differences of Two Asbestos Mines, Boryoung Area

This study is for the genetic differences of two closed asbestos mines from Jeongjeon and Ocheon areas in Boryoung, Chungnam. They are mined asbestos for past several decades. Host rocks are serpentinites for Jeongjeon mine and dolomites for Ocheon mine. Asbestos samples and their host rocks are collected from the field trips and examined with microscopes and FESEM, and analysed with XRD and EDX to confirm for the type and/or compositions of the minerals. The asbestos occur as layers, cracks and fractures assummed as a pathway of the hydrothermal water, but show different characteristics. The serpentinites from the Jeongjeon mine contain chrysotile, tremolite and actinolite asbestos. Non-asbestos minerals including tremolite and actinolite were also found. The chrysotiles occur as a cross fiber or slip fiber at veins and along cracks of several mm to cm thickness. Tremolite and actinolite asbestos occur along cracks and fractures of several cm to ten cm thickness. It suggests that the asbestos from Jeongjeon area were formed by the reactions between serpentinite and hydrothermal water. The dolomites of the Ocheon mine only contain tremolite and actinolite asbestos. The asbestos occur along layers, cracks and fractures, suggestive of asbestos from Ocheon area formed by the reactions between dolomite and hydrothermal waters influxed along layers, cracks and fractures. Overall results suggest that two asbestos mines showing different host rocks are located in a Boryoung area. They show a different type of asbestos minerals, reflecting variety of petrogeneses.