A review of mineral resources in Malawi: With special reference to aluminium variation in mineral deposits

Geochemistry of Monazite within Carbonatite Related REE Deposits

“…In thin sections, monazite appears in a variety of colors, from colorless to yellowish, greenish, and brownish [9,10] (e.g., Figure 2c,d). More commonly, it is the product of metasomatic/hydrothermal alteration of the primary mineral assemblage within the carbonatite …”

“…In thin sections, monazite appears in a variety of colors, from colorless to yellowish, greenish, and brownish [9,10] (e.g., Figure 2c,d). More commonly, it is the product of metasomatic/hydrothermal alteration of the primary mineral assemblage within the carbonatite (e.g., apatite) or occurs along the fractures of the matrix carbonate as interstitial fillings or form veinlets or, which appears as fine-grained polycrystalline clusters (e.g., Figure 2e,f, or Figure 3) [11].…”

“…Though monazite can survive at temperatures much higher than 750 °C, in carbonatite it is restricted to temperatures lower than 750 °C [20]. [21]; (b) disseminated monazite within dolomite marble from Bayan Obo, Inner Mongolia, China; (c) yellow monazite crystals crystallized on the rim of albite matrix from Evate, Mozambique [9]; (d) green monazite occurs as disseminations in the strontianite matrix in Kangankunde, Malawi [10]; (e) BSE image of anhedral monazite in carbonatite from Mountain Pass, the United States [21]; (f) monazite in strongly foliated dolomite carbonatite with quartz laminae from the Cummins Range carbonatite, Australia [22]; (g) monazite net of veinlets in dolomite from Seligdar apatite deposit, Russia [11]; (h) backscattered electron image showing a vug in dolomite filled with potassium feldspar and monazite from the Wideeda carbonatite, Canada [12]; (i) monazite aggregates together with molybdenite in the calcite carbonatite from Huanglongpu, China; (j) euhedral monazite core with small monazite grains in the cracked and resorbed rim from the Hongcheon complex, Korea [14]; (k,l) typical monazite-pyrochlore-crandallite ore in the Tomtor deposit (Russia); and relict pyrochlore crystal in monazite and goyazite as colloform globular segregations in a colloform goethite aggregate [23]. Ab = albite; Ank = ankerite; Ap = apatite; Mnz = monazite; Dol = dolomite; [21]; (b) disseminated monazite within dolomite marble from Bayan Obo, Inner Mongolia, China; (c) yellow monazite crystals crystallized on the rim of albite matrix from Evate, Mozambique [9]; (d) green monazite occurs as disseminations in the strontianite matrix in Kangankunde, Malawi [10]; (e) BSE image of anhedral monazite in carbonatite from Mountain Pass, the United States [21]; (f) monazite in strongly foliated dolomite carbonatite with quartz laminae from the Cummins Range carbonatite, Australia [22]; (g) monazite net of veinlets in dolomite from Seligdar apatite deposit, Russia [11]; (h) backscattered electron image showing a vug in dolomite filled with potassium feldspar and monazite from the Wideeda carbonatite, Canada [12]; (i) monazite aggregates together with molybdenite in the calcite carbonatite from Huanglongpu, China; (j) euhedral monazite core with small monazite grains in the cracked and resorbed rim from the Hongcheon complex, Korea [14]; (k,l) typical monazite-pyrochlore-crandallite ore in the Tomtor deposit (Russia); and relict pyrochlore crystal in monazite and goyazite as colloform globular segregations in a colloform goethite aggregate [23].…”

Morphology and mineral chemistry of monazite–zircon-bearing stream sediments of continental placer deposits (SE Germany): Ore guide and provenance marker

“…The surrounding gneisses pertain to the cordierite-sillimanite facies indicative of temperatures slightly higher (650°C) than the temperature determined for the pegmatite itself (500 to 600°C) (Holdaway and Lee, 1977). Examples from the pegmatite in northern Norway, from Malawi and the San Luis pegmatite province, NW Argentina, corroborate this idea of types III and IV zircon to be used as an ore guide to and within a pegmatite province (Dill, 2007;Oyarzábal et al, 2009;Pedersen et al, 1989;Roberts et al, 2006) (Fig. 9).…”

Evidências de desregulação endócrina causada pela exposição aquática ao alumínio e ao manganês em Astyanax bimaculatus (Linnaeus, 1758)

“…O minério de importância industrial para obtenção do Al é a bauxita, que se forma em regiões tropicais e subtropicais pela força das intempéries (Constantino et al, 2002). A forma natural do óxido de alumínio (α-Al 2 O 3 ) é utilizada industrialmente como um abrasivo e a forma Al (OH) 3 tem aplicação direta nas indústrias de papel, tintas, vidros, cerâmicas, cremes dentais e retardantes de chamas (Dill, 2007 No pH neutro encontrado na maioria das águas naturais, a concentração de Al dissolvido (biodisponível) geralmente é baixa devido a pouca solubilidade do Al mineral, a hidrólise e a formação de Al (OH) 3 e a alta reatividade de hidróxidos polimerizados deste metal com ligantes insolúveis orgânicos e inorgânicos; contudo este metal é altamente solúvel em pH < 6,0 e > 9,0, (Vázquez et al, 2010).…”