GEOLOGY

Detailed explanation-1: -Quartz (Figure 5a) has a vitreous lustre, as do many other silicate minerals, such as feldspar. When transparent, like window glass or clear coloured glass, the term ‘glassy’ lustre may be used instead of vitreous: quartz, for example, often has a glassy lustre.

Detailed explanation-2: -1.13 illustrates that quartz is glassy; galena has a metallic luster, and amber is resinous. In this view, minerals that are as brilliantly reflective as diamond have an adamantine luster.

Detailed explanation-3: -Vitreous minerals have the lustre of glass. (The term is derived from the Latin for glass, vitrum.) This type of lustre is one of the most commonly seen, and occurs in transparent or translucent minerals with relatively low refractive indices.

Detailed explanation-4: -A bright, translucent, vitreous luster usually distinguishes quartzite megascopically from chert, which is opaque with a dull waxy luster, and vein quartz, which has a dull vitreous luster and a cloudy or milky white appearance.

Detailed explanation-5: -This luster is sometimes called “glassy.” Many specimens of apatite, beryl, fluorite, and quartz have a vitreous luster.