Dumortierite in Quartz

GIA and the Smithsonian report this material from western Bahia State, Brazil, near the Vaca Morta quarry in the Serra do Espinhaço range. Quartz there was first found in late 2013 with fine needle-like inclusions or blue clouds of dumortierite; from late 2014 to early 2015 further material appeared with thicker bluish grey needles. The Smithsonian describes this as apparently the first find of well-formed, eye-visible dumortierite crystals in rock crystal quartz. The retailer Pascle also names the USA and Madagascar as sources, which the scientific sources read here do not mention.

The host is quartz (refractive index 1.544 to 1.553, specific gravity about 2.65). GIA identified the blue needles as dumortierite by Raman analysis and saw very strong blue to colorless pleochroism in them under polarized light; some needles look brownish because of staining along the boundary between needle and quartz. This transparent material should not be confused with opaque blue dumortierite-quartz rock: GIA reported such rock submitted as sapphire, with a spot refractive index near 1.55 but a specific gravity of 2.99, too high for quartz, identified by Raman spectroscopy. IGS lists "California lapis" as a misnomer for dumortierite quartz.

IGS lists no special care instructions for quartz. The retailer Pascle advises not leaving this stone in sunlight for long periods because its colour may change; none of the scientific sources read here addresses this.

The retailer Pascle associates dumortierite in quartz with thinking and concentration and suggests it as a charm for students preparing for examinations; it says the stone is believed to help its owner keep to their own will. These are retailer beliefs, not verified properties.