GOLD IN PLANT: USING A PLANT SPECIES (Funtumia elastica) IN PROSPECTING FOR GOLD MINERALISATION AROUND IPERINDO, SOUTHWESTERN NIGERIA

Abstract

Iperindo gold deposit is one of the few primary gold mineralization deposits in Nigeria and the area is underlain by rocks of Precambrian basement complex. Despite previous studies on geology, petrology, mineralogy, petrochemistry, geophysics and geochemistry, no attempt has been made on biogeochemistry of plant present in this area using Scanning Electron Microscopy coupled with Energy Dispersive Spectroscopy (SEM-EDX). This work is therefore targeted at prospecting for gold using bark-scrapings of wild-native, deep rooted and perennial plant species known as Funtumia elastica. Rock units such as faulted migmatite gneiss, banded gneiss, granite gneiss, biotite-hornblende-gneiss, mica schist, quartzite/quartz schist and granite were identified. Eight representative samples of the tree bark were scraped to collect the soft outermost layer. The samples were air dried to prevent fungal and microorganism growth which can contaminate them. Laboratory preparation involved oven-drying at 105˚C for 24 hours. The dried samples were pulverised and sieved using ≥ 125 μm mesh size. The carbon coated samples were scanned at a magnification of ≥ 1000 times its original size to study the plant mineralogy and to infer gold mineralisation in underlying regolith or bedrock.
Surface morphology of the samples as revealed by SEM is homogeneous in composition. Two contrasting compositions are common to all the SEM images studied- an embedded grain clusters showing bright resolution within a matrix of dull resolution. EDX showed average concentration (wt %) of elements such as Ca (11.91), C (59.9), O (21.06), K (1.01), Si (0.14) and Te (6.03). Presence of Te which is associated with gold mineralisation indicates possibility of detecting gold in locations where Te is available.