Mineralogy and sand surface morphology of some volcanic ash soils from West Sumatra Indonesia

Siti Zauyah Darus, . and Shamshuddin Jusop, . and Fauziah Ishak, . and Van Ranst E., . and Fiantis D., . (1998) Mineralogy and sand surface morphology of some volcanic ash soils from West Sumatra Indonesia. [Proceedings Paper]

Volcanic ash soils from Mt. Marapi and Mt. Pasaman in West Sumatra Indonesia were studied to characterize their mineralogy and the surface morphology of the sand grains. The minerals in the sand grains include quartz etched feldspars halloysite and glass having different surface morphology. Halloysite exists as tubular crystals on the weathered grain surface. SEM-EDX gave strong peaks of Si and Al but a weak peak of Fe confirming the presence of halloysite. The clay fraction composes mainly of noncrystalline materials cristobalite feldspars and halloysite. Allophane is abundant in this fraction. Soils of the Mt Pasaman have some gibbsite while those of the Mt. Marapi have opaline silica in the surface horizons. The abundance of opaline silica tends to decrease with the age of the volcanic ash soils. The sand particles have a large variety of morphologies. The morphological features observed are bubblels pitted curve platy and amorphous spheres to cryptocrystalline overgrowth. Some of the sand grains are coated with irregular and spherical-shaped aggregates.

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Abstract

Volcanic ash soils from Mt. Marapi and Mt. Pasaman in West Sumatra Indonesia were studied to characterize their mineralogy and the surface morphology of the sand grains. The minerals in the sand grains include quartz etched feldspars halloysite and glass having different surface morphology. Halloysite exists as tubular crystals on the weathered grain surface. SEM-EDX gave strong peaks of Si and Al but a weak peak of Fe confirming the presence of halloysite. The clay fraction composes mainly of noncrystalline materials cristobalite feldspars and halloysite. Allophane is abundant in this fraction. Soils of the Mt Pasaman have some gibbsite while those of the Mt. Marapi have opaline silica in the surface horizons. The abundance of opaline silica tends to decrease with the age of the volcanic ash soils. The sand particles have a large variety of morphologies. The morphological features observed are bubblels pitted curve platy and amorphous spheres to cryptocrystalline overgrowth. Some of the sand grains are coated with irregular and spherical-shaped aggregates.

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Item Type:	Proceedings Paper
AGROVOC Term:	MINERALOGICAL SOIL TYPES
AGROVOC Term:	SAND
AGROVOC Term:	VOLCANIC SOILS
AGROVOC Term:	CHEMICOPHYSICAL PROPERTIES
AGROVOC Term:	SAMPLING
AGROVOC Term:	X RAYS
AGROVOC Term:	MICROSCOPY
AGROVOC Term:	INFRARED SPECTROPHOTOMETRY
AGROVOC Term:	CLAY
AGROVOC Term:	SOIL MICROMORPHOLOGICAL FEATURES
Geographical Term:	MALAYSIA
Depositing User:	Ms. Norfaezah Khomsan
Last Modified:	24 Apr 2025 05:27
URI:	http://webagris.upm.edu.my/id/eprint/16335

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