PHOSPHORUS-BEARING MINERAL IN FRESH, ANDESITE AND RHYOLITE TEPHRAS IN NORTHERN PART OF JAPAN

Abstract

The occurrence of apatite was confirmed in three unweathered andesite and rhyolite tephras from the northern part of Japan. The apatite mineral was identified using a scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDX). The apatite mostly occurred as inclusions in the heavy minerals. The apatite was soluble in an acidic soil testing solution (Truog method) to determine plant-available phosphorus (P) in the soil.