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Minerals containing metallic bonds are generally characterized by the following features:

1 Fairly soft to moderately hard minerals.

2 Deform plastically; malleable and ductile.

3 Excellent electrical and thermal conductors.

4 Frequently high specific gravity.

5 Excellent absorbers and reflectors of light; so are commonly opaque with a metallic luster in macroscopic crystals.

Transitionalhybrid bonds

electronegativity difference

2

ssss1 Graph showing the electronegativity difference and bond type in covalent–ionic bonds. Percent covalent bonding is indicated by the black line and percent ionic bonding by the blue line.

This simple picture of transitional ionic–covalent bonding does not hold in bonds that involve transition metals. For example, the mineral galena (PbS) has properties that suggest its bonding is transitional between metallic and ionic. In this case some electrons are partially transferred from lead (Pb) to sulfur (S) in the manner characteristic of ionically bonded substances, but some electrons are weakly held in the manner characteristic of metallic bonds. As a result, galena displays both ionic properties (brittle and somewhat soluble) and metallic properties (soft, opaque and a metallic luster). ssss1 utilizes a triangle, with pure covalent, ionic and metallic bonds at the apices, to depict the pure and transitional bonding characteristic of selected minerals, including those discussed above.