KAITAN SIFAT MAGNETIK DENGAN TINGKAT KEHITAMAN (DARKNESS) PASIR BESI DI PANTAI MASANG SUMATERA BARAT

Abstract

Iron sand is one of the natural resources found in abundant in West Sumatera, yet has not been exploited and utilized optimally. One of the deposits of iron sand is located in coast of Masang, Agam Regency, West Sumatera. The deposit cross section of the iron sand in coast of Masang forms layers with different levels of darkness. This might happen because of the season changes during the deposit formation process. This research aims to explore the correlation between darkness level of the iron sand and its magnetic characteristics. The sampling process was conducted by taking five samples vertically on the deposit cross section which formed different darkness level layers. The magnetic characteristics measured were the samples’ magnetic susceptibility, the kinds of magnetic minerals and the size of mineral grains. The measurement employed were magnetic susceptibility, ARM and IRM. The data were analyzed by plotting ARM decay curve and IRM saturation curve toward magnetic samples’ intensity value. The results of the measurement indicate that the iron sand samples with the highest darkness level have high susceptibility value, and vice versa. The result of the IRM saturation curve indicates that the kind of dominant minerals in samples is magnetite. The highest saturation intensity is also found in samples with high darkness level, which indicates that the magnetic mineral concentration is also high. The result of the ARM decay curve indicates that the size of the magnetic granules are quite big, belong to multidomain (MD).

Keyword : magnetic properties, darkness, iron sand, coast of Masang West Sumatera