Give students an assortment of minerals and a sorting sheet.
Ask them to look closely at the surface texture, and sort the minerals onto the sheet.
It doesn't matter if they don't get it exactly right (it takes much experience). The point is to notice different surface textures and reflectiveness in different minerals.
The technical lustre descriptions:
(from https://www.minerals.net/resource/property/luster.aspx)
Metallic - Minerals with a metallic luster are opaque and reflective, like metal.
The metallic elements, most sulfides, and some oxides belong in this category.
Submetallic - Describes a mineral that is opaque to nearly opaque and reflects well. Thin splinters or sections of submetallic minerals are translucent.
Vitreous (also called glassy) - Minerals with a vitreous luster have reflective properties similar to glass.
This luster accounts for roughly 70 percent of all minerals. Most of the silicates, carbonates, phosphates, sulfates, halides, and hydroxides have a vitreous luster.
Adamantine - Transparent to translucent minerals with a high refractive index yield an adamantine luster, meaning they display extraordinary brilliance and shine. Diamond.
Resinous - This is the luster of many yellow, dark orange, or brown minerals with moderately high refractive indices - honey like, but not necessarily the same color.
Silky - A silky luster is the result of a mineral having a fine fibrous structure. Minerals with a silky luster have optical properties similar to silk cloth.
Pearly - Describes a luster similar to the inside of a mollusk shell or shirt button. Many micas have a pearly luster, and some minerals with a pearly luster have an iridescent hue. Some minerals may exhibit a pearly luster on cleaved crystal surfaces parallel and below the reflecting surface of a mineral.
Greasy - Luster of a mineral that appears as if it were coated with grease.
Pitchy - Minerals with a tar-like appearence have a pitchy luster. Minerals with a pitchy luster are usually radioactive and have gone through the process of metamiction.
Waxy - A waxy luster describes a mineral that appears as if it were coated with a layer wax.
Dull - This luster defines minerals with poor reflective qualities, much like unglazed porcelain. Most minerals with a dull luster have a rough or porous surface.
