submetallic

Submetallic is a mineralogical term used to describe a luster that lies between metallic and nonmetallic. It refers to a surface that has a metal-like sheen but is less reflective and often appears somewhat dull, pale, or cloudy compared with a true metallic luster. Submetallic luster can resemble tarnished metal and may become more apparent under diffuse lighting. It is one of several standard luster categories used to describe how minerals reflect light.

The term is subjective, varying with the observer and lighting conditions. Differences from metallic luster include lower reflectivity, more muted highlights, and sometimes a dull or waxy appearance. Submetallic surfaces may still show bright reflections at sharp angles but lack the sharp brilliance of metallic specimens.

Submetallic luster commonly occurs in minerals such as hematite and in some weathered or tarnished sulfide minerals; goethite and certain oxides can also display submetallic luster. The attribute is typically cataloged in hand specimens and thin sections to aid identification and description, along with color, hardness, streak, and fracture.

The word is used mainly in mineralogy and gemology as a descriptor rather than as a distinct material category. It does not imply a fixed chemical class, but rather a superficial optical property that can vary with surface condition and weathering.