Other rare earth oxides such as fergusonite , samarskite and euxenite have very similar properties to aeschynite and are often associated with each other, compounding the problem. Even the common oxide, rutile , is almost indistinguishable from these rare earth oxides without chemical tests when rutile is found massive. Aeschynite is found in rare earth rich granite pegmatites, a slow cooling igneous intrusive rock. Aeschynite is associated with minerals such as quartz , feldspars , zircon , columbite , xenotime , monazite , tantalite and other rare earth minerals. Aeschynite forms well shaped crystals at times, is associated with other rare minerals and can be an interesting specimen in someone's collection.
Color is black to dark brown or yellowish brown in smaller crystals.
Luster is vitreous to adamantine or pitchy when more massive. Crystals are nearly opaque in massive forms and translucent in small crystals. Crystal Habits include tabular to prismatic almost blocky crystals, some with well formed domal terminations. Cleavage is absent. Fracture is conchoidal.