Composition and dissolution kinetics of garnierite from the Loma de Hierro Ni-laterite deposit, Venezuela
- 作者：Josep M. Soler ; Jordi Cama ; Salvador Galí ; Williams Melé ; ndez ; Arm ; o Ramí ; rez ; José ; Estanga
- 关键词：Garnierite ; Nickel ; Laterite ; Serpentine ; Talc ; Dissolution
- 刊名：Chemical Geology
- 出版年：2008
- 期刊代码：12_00092541
- 类别：ear
- 出版时间：30 March 2008
- 卷：249
- 期：1-2
- 页码：191-202
- 文件大小：1312 K
摘要
The composition of a garnierite sample (Mg–Ni silicate) from the Loma de Hierro Ni-laterite deposit (Venezuela) has been determined by means of X-ray diffractometry (XRD), high-resolution transmission electron microscopy (HR-TEM) and electron microprobe (EM) analyses. This garnierite was collected from a vein in the parent rock of the laterite (serpentinized peridotite). XRD showed peaks at 7 Å and 10 Å, characteristic of the structures of serpentine and talc, respectively. HR-TEM revealed different areas characterized by either a 7 Å or 10 Å spacing. EM showed a homogeneous sample composition, with a (Mg + Ni)/Si ratio equal to 0.92. The stoichiometric formula for this garnierite is given by Mg2.91Ni0.09Si3.27O8.17(OH)2.74, which corresponds to a mixture of Ni-containing serpentine (37 mol%) and talc (63 mol%). EM analyses were also performed on six additional samples from the main Ni enrichment zone of the laterite. The results show a clear correlation between Ni content and mole fraction of talc, indicating the affinity of Ni for the talc phase in the garnierite. Quantitative XRD fitting of one of these additional samples indicated that the talc belongs to the variety known as kerolite.