I'rĭ-dŏs'mĭne or I'rĭ-dŏs'mĭ-ŭm, n.

n. [From iridium and osmium, q. v.] (Min.) The native compound of iridium and osmium. It is found in flattened metallic grains of extreme hardness, and is often used for pointing gold pens. Dana.