A thin needle-shaped or acicular crystal, which is an inclusions in certain minerals, such as rutilated quartz, sapphire, or corundum. Sometimes actinolite, goethite, etc. appear in certain crystals.
See Alexandrite Tsarstone collectors guide, Definition of Needle, http://w.alexandrite.com/viewpage.html?id=GG-099-00002 (A thin needle-shaped or acicular crystal, which is an inclusions in certain minerals, such as rutilated quartz, sapphire, or corundum. Sometimes actinolite, goethite, etc. appear in certain crystals. ) (as of Apr. 06, 2026, 18:43 GMT).