CHEMICAL, PHYSICAL AND MINERALOGICAL CHARACTERIZATION OF OVERBURDEN ROCK AND IRON MINE SPOIL AT ALEGRIA IRON MINE, MARIANA-MG

Abstract

In the area under the Alegria iron mine influence (Mariana, Minas Gerais, Brazil), samples of fours materials were collected, identified as phyllite, soil, overburden rock, and mine spoil, for chemical, physical, and mineralogical characterization. All four materials are poor in plant macro and micronutrients, presenting low amounts of organic carbon and physical characteristics which hinder the development of plant root system. The high bulk density and particle density values of all materials are related to the presence of heavy minerals, mainly Fe oxides. Except for phyllite, which presented considerable amounts of silt, the materials presented high amounts of sand: more than 50%. As far as water retention is concerned, the phyllite showed the highest retention but it could be detrimental to plant growth due to excess of water and surface sealing. The mineralogy of sand, silt, and clay fractions is basically constituted by goethite, hematite, and quartz, while phyllite presents, besides these minerals, kaolinite, microcline, gibbsite, and mica.

KEY-WORDS: Iron mining; mineralogical characterization; iron mine spoil.