Visual inspection of the dark gray rock suggested that it was probably a fine-grained basaltic igneous rock formed by the crystallization of magma near the planet’s surface.

The coarse gray igneous rocks that look like granite are syenite with sodalite. It's the sodalite that causes the golden fluorescent glow.

Revise the characteristics of igneous, sedimentary and metamorphic rocks and how they are formed over a long period of time.

THE review of the treatise of Beyschlag, Vogt, and Krusch in NATURE of August 3, 1916, gives prominence to their mention of supposed absence of Tertiary igneous rocks. Yet even their pages figure ...

Visual inspection of the dark gray rock suggested that it was probably a fine-grained basaltic igneous rock formed by the crystallization of magma near the planet's surface.