mafic mineral

mafic mineral

[′maf·ik ′min·rəl]
(mineralogy)
A mineral that is composed predominantly of the ferromagnesian rock-forming silicates.
In general, any dark mineral.
References in periodicals archive ?
2013) are characterized by either clinopyroxene or amphibole as the principal mafic mineral.
Three rock types fall under the broad category of "biotite-rich granitoids", which refers to granitoid rocks with relatively high (10-30 modal %) mafic mineral content (predominately biotite) in the SMB.
The characteristic mafic mineral in granites is annitic to siderophyllitic biotite.
The mafic rocks can be divided into two broader types one of which contains hornblende and the other clinopyroxene as characteristic primary mafic mineral.
On the basis of the main mafic mineral content, Laghari (2004) classified the dykes into hornblende-bearing (appinitic) and pyroxene-bearing types.
Further, the petrographic description of the intrusive and metamorphic units describes a widespread weak-to-moderate early and hot potassic alteration, expressed as biotite and K-spar alteration of mafic minerals and K-spar alteration of plagioclase feldspars.
The dense residues of these processes, which would have a high content of mafic minerals, must now reside in the mantle.
To simplify the 40 plus elements analyzed for the ET3 sequence, the tephras have been broken down into three basic components: glass, plagioclase and mafic minerals.
Mafic minerals typically comprise ~10% of the granite.
The more alkalic members of the suite tend to be partially to completely altered, with widespread kaolinite, sericite and replacement of feldspar phenocrysts and mafic minerals by calcite or hematite, or both (Fig.
Ten holes drilled earlier this year in an area of 530 meters by 320 meters intersected a sandy tuff sequence that showed an increasing content of mafic minerals, (olivine and pyroxene) to the north.
The higher grade gold is associated with bornite and carbonate in late stage veins, veinlets and disseminated in the wall rock as altered products of mafic minerals.