TITLE:
Green Gold—Dirty Gold, Tadó, Dept. Chocó, Colombia
AUTHORS:
William E. Brooks, Julio Andrés Sierra-Giraldo, Franciso Mena Palacios
KEYWORDS:
Green Gold, Mercury, Geochemistry, Plants, Colombia
JOURNAL NAME:
Natural Resources,
Vol.6 No.11,
November
16,
2015
ABSTRACT: In place of mercury,
small-scale alluvial gold miners in Tadó, Dept. Chocó, Colombia produce “green
gold” (oroverde) using locally
available plant extracts. The leaves of Balso (Ochroma pyramidale) and Malva (Hibiscus
furcellatus) are
crushed by hand and are mixed with water to make a foamy liquid that is added
to the gold pan (batea) instead of
mercury. After the plant extract is added, the gold, magnetite, and other heavy
minerals sink and the lighter minerals are floated out of the gold pan. For
final clean-up, a combination of other methods may be used. However, ICP
(Inductively Coupled Plasma) analyses indicate that even green gold contains 208
- 4530 ppm Hg—this mercury may have been released from dragas or other small-scale gold mining operations that continue to
use mercury; coal burning; volcanism; or native mercury released from cinnabar
occurrences. ICP also indicates 308 - 106,000 ppm Ag and 452 - 585 ppm Pt.