A dimorph is a mineral that has the same chemistry but a different structure. As mineral specimens, tantalite can be a nice addition to one's collection. Good crystals are both complex and handsome. Although the color selection is usually limited too black to brown the luster is generally good. Manganese rich tantalites can be brown and translucent.
Color is dark black, iron-black to dark brown or even reddish brown.
Luster is submetallic to almost resinous. Crystals are nearly opaque being transparent in thin splinters. Crystal Habits include stubby prismatic crystals with complexly faceted or rounded terminations. Also very flat tabular crystals sometimes aggregated together in parallel or nearly parallel groups. Can also be granular and massive.