Enriched

Gallium resources in different minerals of bauxite and their implications

2 Goethit mit kolloidaler Bänderung einschließlich Hämatit und umgeben von einer Silikatmatrix (oben). Dünne Leisten von Ilmenit mit Silikaten. Probe Jharkhand, Auflichtmikroaufnahmen # Goethite shows colloform banding with hematite and is surrounded by a silicate matrix (top). Thin laths of ilmenite with silicates. Jharkhand Sample, Reflected Light photomicrographs

3 Hämatit von Silikaten umgeben (oben) und von Goethit eingeschlossen. Rutil in der Silikatmatrix und Gibbsit-Oolithe mit Silikat-Oolithen (unten). Probe Jharkhand, Auflichtmikroaufnahme # Hematite enclosed by silicates (top) and enclosed by goethite. Rutile within the silicate matrix and oolites of gibbsite contain silicate oolites (bottom). Jharkhand Sample, Reflected light photomicrograph

4 Freigesetzte oolithische und pisolithische Kügelchen aus Eisen- (schwarz) und Aluminiumphasen (oben). Die oolithischen und pisolithischen Kügelchen unterschiedlicher Phasen weisen Verkrustungen unterschiedlicher Schichten übereinander auf. Sie liegen über den tonhaltigen Eisenphasen, Gibbsit, Ton (C) und Quarz (Q) als Einschlüsse (unten). Probe Gujarat, stereomikroskopische Aufnahmen # Liberated oolitic and pisolitic nodules of iron (black) and aluminium phases (top). The oolities and pisolities nodules of different phases show encrustations of different layers one over the other. They lie over the clay containing iron phases, gibbsite, clay (C) and quartz (Q) as enclosures within it (bottom). Gujarat sample, Stereomicroscopic photomicrographs

5 Leistenförmiges Ilmenit (Mikroaufnahme oben) und Leukoxen (verändertes Ilmenit, durch Pfeil gekennzeichnet; Mikroaufnahme unten) im Gibbsit. Probe Gujarat, Auflichtmikroaufnahme # Lath-shaped ilmenite (top photomicrograph) and leucoxene (altered ilmenite, shown by arrow; bottom photomicrograph) present within the gibbsite. Gujarat sample, Reflected light photomicrograph

1 Oolithe von Gibbsit mit Goethit- und Hämatitphasen (oben links Mikroaufnahme) und Gibbsit-Oolithe umgeben von einer Tonmatrix (oben rechts Mikroaufnahme). Eine von einem Gibbsit-Oolithen eingeschlossene Silikatleiste (unten links Mikroaufnahme) sowie Hämatit (weiß) und Goethitmatrix mit Gibbsit assoziiert (unten rechts Mikroaufnahme). Probe Jharkhand, Auflichtmikroaufnahmen # Oolites of gibbsite contain goethite and hematite phases (top left photomicrograph) and gibbsite oolites encircled by clay matrix (top right side photomicrograph). A lath of silicate is enclosed by gibbsite oolite (bottom left photomicrograph) and hematite (white) and goethite matrix is associated with gibbsite (bottom right photomicrograph). Jharkhand Sample, Reflected light photomicrographs

Dr. Danda Srinivas Rao

Dr. B. Das

Summary: The distributions of gallium (Ga) of two different, geologically and geographically apart, bauxite deposits in India (Jharkhand and Gujarat) with respect to their different mineralogical phases were studied. The samples were studied under the optical microscope for their mineralogy and the electron microscope, attached with energy-dispersive X-ray spectrometer, to investigate the quantitative distribution and occurrence of gallium in various mineral phases. The investigation revealed the presence of gibbsite, boehmite, hematite, goethite and ilmenite in both the deposits but no separate gallium-bearing mineral phase could be identified in either of the deposits. The studies indicated that different mineral phases such as gibbsite and boehmite contain 0.09 to 0.53 % of Ga. Iron oxide phases like hematite and goethite contain 0.46 to 0.74 % Ga, whereas 0.20 to 0.96 % of Ga is present in the ilmenite phases. The association of gallium in these phases could be mainly due to adsorption during genesis.

1 Introduction

Gallium (Ga) is a rare, soft silvery metallic element with the atomic number of 31. It enjoys vast application in optoelectronics (e.g., LED’s), telecommunication, aerospace, and many commercial as well as household items such as alloys, computers and DVD’s. Over 95 % of gallium is now used in semi-conductors. Countries such as Australia, China, Germany, Kazakhstan, Japan and Russia are the main suppliers of primary gallium while France is the largest single source of refined gallium in the world [13]. Gallium minerals are very rare and no distinct ore deposits from which...