Red Rutilated Quartz

GIA reported transparent quartz with bright reddish rutile needles from a deposit in Bahia, northern Brazil, that was worked decades ago, closed, and has been reopened in recent years because of the rising value of rutilated quartz.

Rutile's recorded colours include blood red and brown-red. A Chinese study found that the red "hair crystal" sold in the market contained rutile, whereas purplish-red flaky inclusions in other quartz were hematite, goethite and lepidocrocite. Raman spectroscopy separates them: rutile peaks near 445 and 600 cm⁻¹, hematite at a different set including about 225 and 300 cm⁻¹.

The host is quartz, with a Mohs hardness of 7. JCK advises washing off dust before wiping the stone with a cloth, because dust of similar hardness can leave fine scratches that gradually dull the polish. The International Gem Society lists no special care instructions and no heat sensitivity for quartz.

The name rutile, introduced by the German geologist Abraham Gottlob Werner in 1800, comes from the Latin rutilus, "reddish". Earlier, in 1783, Romé de l'Isle called the mineral "red or purple schorl" when describing it as inclusions in quartz from Madagascar.