Rock crystal may contain two-phase inclusions often gas or carbon dioxide but several minerals give rock crystal an unexpectedly exotic appearance. Reddish or golden rutile crystals in hair-like form produce rutilated quartz. Other long and slender inclusions may include tourmaline or actinolite. In some cases the actinolite is sufficiently green to color the host. Other inclusions are blue anatase, ilmenite, boulangerite, giessenite, heyrovskyite, brownish yellow goethite, lepidocrocite, reddish hematite, chlorite, pyrochlore, and spessartite. Chyrsocolla or dumortierite may produce blue or brown colors. |
