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Copper-nickel Mineralization in a Drill Core from the Duluth Complex of Northern Minnesota.

Authors
Boucher-ML
Source
NTIS: PB 249 736 :55 pages
Link
NIOSHTIC No.
10007602
Abstract
Copper and nickel sulfides occurring in the Duluth complex of northern Minnesota were examined at the Bureau of Mines. A microscopic study was undertaken to determine the mineralogy and paragenesis of the ore minerals. Eighty-two samples were taken from one deep diamond drill core located near Babbitt, Minnesota. Modal analyses are presented for the Duluth Complex rocks and for the ore minerals in the major mineralized zone. The major sulfide minerals are chalcopyrite, cubanite, pyrrhotite, troilite, and pentlandite. Results of this investigation suggest that the mineralization is related to the structural features of the enclosing rocks: pores, open fractures, and cavities. The pyrrhotite-troilite-pentlandite assemblage is believed to have formed from an immiscible sulfide melt, probably associated with the troctolitic rocks. Most of it settled to the very porous base of the Duluth Complex, and to the other porous zones near xenoliths; small portions were trapped higher in the section. A later introduction of a copper-rich sulfide melt replaced some of the pyrrhotite-troilite and oxides, and filled in the remaining open spaces and fractures in the Duluth Complex and those of the adjacent footwall rock.
Publication Date
19750101
Document Type
IH; Report of Investigation;
Fiscal Year
1975
NTIS Accession No.
PB-249736
NTIS Price
A05
Identifying No.
RI 8084
NIOSH Division
TCRC;
Source Name
NTIS: PB 249 736
State
MN;
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