Orthoamphibole, clinoamphibole and magnetite are common minerals in altered rocks associated spatially with Palaeoproterozoic volcanogenic massive sulfide (VMS) deposits in Colorado, USA and metamorphosed to the amphibolite facies. These altered rocks are dominated by the assemblage orthoamphibole (anthophyllite/gedrite)–cordierite–magnetite±gahnite±sulfides. Magnetite also occurs in granitoids, banded iron formations, quartz garnetite, and in metallic mineralisation consisting of semi-massive pyrite, pyrrhotite, chalcopyrite, and sphalerite with subordinate galena, gahnite and magnetite; amphibole also occurs in amphibolite. The precursor to the anthophyllite/gedrite–cordierite assemblages was probably the assemblage quartz–chlorite formed from hydrothermal ore-bearing fluids (~250° to 400°C) associated with the formation of metallic minerals in the massive sulfide deposits.

Element–element variation diagrams for amphibole, magnetite and ilmenite based on LA-ICP-MS data and Principal Component Analysis (PCA) for orthoamphiboles and magnetite show a broad range of compositions which are primarily dependent upon the nature of the host rock associated spatially with the deposits. Although discrimination plots of Al/(Zn+Ca) vs Cu/(Si+Ca) and Sn/Ga vs Al/Co for magnetite do not indicate a VMS origin, the concentration of Al+Mn together with Ti+V and Sn vs Ti support a hydrothermal rather than a magmatic origin for magnetite. Principal Component Analyses also show that magnetite and orthoamphibole in metamorphosed altered rocks and sulfide zones have distinctive eigenvalues that allow them to be used as prospective pathfinders for VMS deposits in Colorado. This, in conjunction with the contents of Zn and Al in magnetite, Zn and Pb in amphibole, ilmenite and magnetite, the Cu content of orthoamphibole and ilmenite, and possibly the Ga and Sn concentrations of magnetite constitute effective exploration vectors.

正角闪石、斜角闪石和磁铁矿是蚀变岩石中的常见矿物，这些岩石与美国科罗拉多州古元古代火山成因块状硫化物 (VMS) 矿床空间相关，并变质为角闪岩相。这些蚀变岩主要由正角闪石组合（直闪石/闪锌矿）-堇青石-磁铁矿±辉石+硫化物组成。磁铁矿也出现在花岗岩、带状铁矿、石英石榴石以及由半块状黄铁矿、磁黄铁矿、黄铜矿和闪锌矿以及次要的方铅矿、锌尖石和磁铁矿组成的金属矿化中；角闪石也出现在角闪岩中。直闪石/堇青石-堇青石组合的前体可能是由与块状硫化物矿床中金属矿物形成相关的热液含矿流体（~250°至400°C）形成的石英-绿泥石组合。

基于 LA-ICP-MS 数据和正闪石和磁铁矿的主成分分析 (PCA) 的角闪石、磁铁矿和钛铁矿的元素-元素变化图显示了广泛的成分，这些成分主要取决于与空间相关的主岩性质存款。尽管磁铁矿的 Al/(Zn+Ca) 与 Cu/(Si+Ca) 和 Sn/Ga 与 Al/Co 的判别图并不表明 VMS 来源，但 Al+Mn 以及 Ti+V 和 Sn 的浓度与钛支持磁铁矿的热液成因而不是岩浆成因。主成分分析还表明，变质蚀变岩和硫化物带中的磁铁矿和正角闪石具有独特的特征值，使它们可以用作科罗拉多州 VMS 矿床的潜在探路者。这与磁铁矿中 Zn 和 Al 的含量、角闪石、钛铁矿和磁铁矿中 Zn 和 Pb 的含量、正角闪石和钛铁矿中的 Cu 含量以及可能的磁铁矿中 Ga 和 Sn 的含量构成了有效的勘探向量。