Journal of the Mineralogical Society of Korea (한국광물학회지)

The Mineralogical Society of Korea (한국광물학회)
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Laboratory Weathering Experiment on Mica and Feldspar and Their Mineralogical Characteristics

운모와 장석의 실내 풍화실험 및 광물학적 특성

  • Published : 2006.06.01
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Abstract

When rocks are exposed to the near surface environment, they are broken down due to several factors such as physical and chemical weathering during the geologic time. The feldspar and mica, which are the main rock-forming minerals, are easily broken down relative to other minerals. In order to reproduce some weathered minerals similar to the ones exist in natural weathered granite, there was an experimental interaction between fresh minerals and acidic solution. In low pH condition, biotite initially dissolved and its surface structure broke down, whereas plagioclase dissolved and had a needle-shaped dissolved morphology with some precipitates composed of Al element. The minerals were deeply dissolved in a strong acid condition, showing the prominent dissolved structure. Some etch pits and dissolved textures developed on the natural mineral surfaces are similarly found in our experiment, suggesting the development of mineral dissolution and weathering texture by the influence of the mineral's intrinsic nature.

암석은 지표환경에 노출되면 오랜 세월동안 여러 요인에 의해 물리적 화학적 품화과정을 겪는다. 암석을 구성하는 광물 중 장석과 운모는 다른 광물들에 비해 가장 먼저 풍화되는 광물들이다. 자연계 풍화 화강암내에 존재하는 풍화 광물과 유사한 풍화 광물을 재현하기 위해 실내에서 신선한 광물과 산성용액과의 반응실험을 실시하였다. 흑운모의 경우, 낮은 pH조건에서 광물 용해 및 표면구조 파괴 현상이 초기에 시작되어 점차 진행되었고 사장석에서는 표면 침상 용해구조 발달 및 다량의 Al 성분의 침전물 형성이 두드러졌다. 강산조건에서는 모든 광물의 용해가 심화되었고 표면 용해구조가 뚜렷이 나타났다. 야외에서 관찰되는 광물표면의 용식각(etch pit) 및 표면 용해구조가 본 실험에서도 비슷하게 관찰되었고 광물 용해 및 풍화 조직이 광물 고유의 특성에 따라 발달됨을 알 수 있었다.

Keywords

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