Gahnite Composition: Implications for Base Metal and Rare-element Exploration

Gahnite, a zinc-bearing spinel, is a resistate mineral that may be used as
an indicator mineral of polymetallic deposits in high-grade metamorphic terrain.
The Ontario Geological Survey recently completed surficial mapping and sampling
programs in the Separation Lake area of northwestern Ontario and Kinniwabi Lake
area of northeastern Ontario in which gahnite was recovered from samples of
surficial sediments. Ternary plots of the composition (ZnO, MgO, FeO[t]) of
gahnite recovered from these surficial studies reveal three distinct groups:
Group 1 is characterized by low (< 1 wt%) MgO values; Group 2 by higher
(>1 wt%) MgO values; and Group 3 by higher FeO(t) values than Groups 1 and 2.
The composition of in situ gahnite recovered from volcanogenic massive sulfide
mineralization, Zn-rich Sedex-type mineralization and peraluminous rare-element
mineralized granite and pegmatite also was determined. The composition of the
gahnite obtained from surficial samples was compared with that of in situ
material. Gahnite from the peraluminous rareelement granite and pegmatite
overlapped very well with surficial gahnite of Group 1. Gahnite from
volcanogenic massive sulfide mineralization and Sedex-type mineralization
overlapped well with surficial gahnite of Group 2. These results suggest that
determination of gahnite composition in indicator mineral surveys may be useful
in exploration programs when assessing the mineral potential of a
Keywords: Gahnite, Resistate mineral, Polymetallic deposits, metamorphic terrain, Mineralization
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Summary: The Geological Society has its own quarterly journal called Exploration
and Mining Geology, for the publication of Canadian and international papers on
applied aspects of mineral exploration and exploitation, including mineral
deposit geology, geochemistry, and geophysics, mining geology, mineral resource
appraisal and estimation methods, environmental geology, and case histories. The
editor of the journal is Jeremy P. Richards
Publication: Exploration & Mining Geology
Issue: 3
Volume: 6
Year: 1997
Summary: Rare earth element (REE) data are reported for ores, sulfide-bearing rocks and host rocks from massive sulfide deposits and barren sulfide facies iron formations in Proterozoic volcanic rocks of the Flin Flon-Snow Lake area, Manitoba. Some of the rare earth elements (e.g., Eu), are selectively leached in zones of intense alteration and redeposited together with the sulfides and silicates in the uppermost parts of the alteration zones and at the rock-water interface. Chondrite normalized REE...
Publication: Exploration & Mining Geology
Author(s): G.H. GALE: Department of Energy and Mines, Geological Services Branch, 1395 Ellice Avenue, Suite 360, Winnipeg, Manitoba, Canada R3G 3P2; L.B. DABEK: Department of Geology, University of Regina, Regina, Saskatchewan, Canada; M.A.F. FEDIKOW: Department of Energy and Mines, Geological Services Branch, 1395 Ellice Avenue, Suite 360, Winnipeg, Manitoba, Canada R3G 3P2
Keywords: Rare earth element, REE, Ores, Massive sulfide deposits, Iron formation, Manitoba, Exploration, Ore equivalent strata
Issue: 3
Volume: 6
Year: 1997
Summary: Gamma-ray spectrometry, an effective tool in geological mapping, was used to define boundaries between various lithological formations in three adjacent areas of Central Syria, namely, the Syrian Desert, Ar Rassafeh Badiayat and the Northern Palmyrides mountains. This paper describes the role of an airborne gamma spectrometric survey which was orginally undertaken to assist uranium exploration. Interpretation of the total count data obtained through the survey has led to significant modificat...
Publication: Exploration & Mining Geology
Author(s): Y.M. JUBELI: Department of Geology and Nuclear Ores, Atomic Energy Commission
P.O. Box 6091, Damascus, Syria
Keywords: Gamma-ray spectrometry, Geological mapping, Syria, Uranium exploration
Issue: 3
Volume: 6
Year: 1997
Web Page
Summary: <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<BODY>To evaluate geochemical aspects of sheared zones, 35 samples of granitoid
rocks from an area of shearing &gt;5 km2 at Derehamzeh, Iran were studied
geochemically. Relatively unaltered samples within the shear-zone area average
38 ppm Cu, 1.45 ppm Mo, 4.6 ppb Au, 0.21 ppm Ag, &lt;1...
Publication: Exploration & Mining Geology
Author(s): A. AFTABI: Department of Geology, Shahid Bahonar University of Kerman, Kerman, Iran
Keywords: Geochemistry, Granitoid rocks, Hydrothermally-altered samples, Porphyry copper mineralization
Issue: 3
Volume: 6
Year: 1997
Summary: The Kori Kollo gold deposit is hosted by a c.15 Ma sericitized dacite stock in the La Joya district on the Bolivian Altiplano. The mineralization is of the Bolivian polymetallic vein (BPV) type, with a significant amount of the gold reserves contained in the oxide cap. Field and microscopic studies, K-Ar dating, ??34S values of pyrite, alunite and jarosite, and ??18O values of alunite and jarosite demonstrate that some of this gold is supergene. Two types of supergene gold are present: minute...
Publication: Exploration & Mining Geology
Author(s): K.E. DARKE: Department of Geology and Petroleum Geology, University of Aberdeen, Aberdeen AB24 3UE, Scotland; A.J. BOYCE: Scottish Universities Research and Reactor Centre, East Kilbride, Glasgow G75 0QF, Scotland; C.M. CLAPPERTON: Department of Geography, University of Aberdeen, Aberdeen AB24 3UE, Scotland; A.E. FALLICK: Scottish Universities Research and Reactor Centre, East Kilbride, Glasgow G75 0QF, Scotland; S.D. REDWOOD: INMET Mining Corporation, Lima 18, Peru
C.M. RICE: Department of Geol
Keywords: Kori Kollo gold deposit, Mineralization, Bolivian polymetallic vein, Oxide-zone mineralogy
Issue: 3
Volume: 6
Year: 1997
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