Dumortierite Quartz: Rare Blue Quartz

Dumortierite quartz is blue colored quartz containing abundant dumortierite inclusions.

Dumortierite quartz is one of the rarer and more unusual blue varieties of quartz gemstones. It is a gemstone-quality combination of quartz aggregate, intergrown with the mineral known as dumortierite. Although quartz can occur in a wide range of colors, blue colored quartz is surprisingly quite rare. The traces of dumortierite are responsible for its distinct color, which can range from light to dark blue and in some cases reddish-brown.

Dumortierite Quartz: Rare Blue Quartz. Dumortierite in quartz From Brazil. Photo: GalaxSea.

How Dumortierite Quartz is Formed

Dumortierite Quartz is a type of quartz that contains dumortierite, a blue-green mineral. It is typically found in hydrothermal veins, which are formed when hot, mineral-rich fluids flow through rocks.

The formation of Dumortierite Quartz begins with the weathering and erosion of rocks that contain dumortierite. This dumortierite is then transported by water or other fluids to a hydrothermal vein.

In the hydrothermal vein, the dumortierite is dissolved by the hot, mineral-rich fluids. The fluids then cool and the dumortierite crystallizes out of solution. This crystallization process can form Dumortierite Quartz in a variety of shapes and sizes.

Dumortierite Quartz is typically found in association with other hydrothermal minerals, such as quartz, calcite, and fluorite. It is often found in veins that are associated with igneous rocks, such as granite and rhyolite.

Dumortierite-quartz specimen - Brazil Photo: James St. John

Dumortierite

Dumortierite is a rare and beautiful mineral that is prized for its vibrant blue color. It is a borosilicate of aluminum, with the chemical formula  Al₇BO₃(SiO₄)₃O₃. Dumortierite typically occurs in fibrous aggregates of slender prismatic crystals, and it can range in color from pale blue to deep violet-blue.

Dumortierite is typically found in fibrous or needle-like crystals that can be up to several centimeters in length. It is also found in massive or granular forms. The color of dumortierite can vary from pale blue to deep blue-green, depending on the iron content.

Dumortierite is found in a variety of geological settings, including high-grade metamorphic rocks, contact metamorphic rocks, and pegmatites. It is also found in some alluvial deposits. The primary sources of dumortierite are Brazil, Madagascar, Sri Lanka, and the United States.

Dumortierite is a relatively hard mineral, with a Mohs hardness of 7 to 8. It is also translucent to opaque. Dumortierite is sometimes mistaken for other blue minerals, such as sodalite and lapis lazuli. However, it can be distinguished from these minerals by its higher hardness and fibrous habit.

The mineral was first described in 1881 and was named after French paleontologist, Eugene Dumortier (1803-1873). Dumortierite also has a few industrial purposes other than jewelry. Since it is known to turn remarkably pure white in color when fired, it is often used for the production of porcelain and ceramics. It is sometimes mistaken for sodalite and has been used as imitation lapis lazuli. 

Quartz with Dumortierite Inclusions Photo © Jeff Scovil

Dumortierite Quartz Physical properties

Dumortierite quartz is typically a blue-green color, but it can also be found in other colors, such as yellow, red, and brown. It is typically transparent to translucent, and it has a vitreous luster. Dumortierite quartz has a Mohs hardness of 7, which makes it a relatively hard gemstone.

• Color: Blue-green
• Hardness: 7-7.5
• Specific gravity: 2.7-2.8
• Refractive index: 1.58-1.60
• Cleavage: None
• Luster: Vitreous

Dumortierite in quartz From Brazil. Photo:  crystalarium

Dumortierite Quartz Uses

Dumortierite quartz is used for a variety of purposes, including:

Jewelry: Dumortierite quartz is a popular gemstone that is used in jewelry. It can be cut into a variety of shapes, including beads, cabochons, and pendants.

Ornamental stones: Dumortierite quartz is also used as an ornamental stone. It can be used in carvings, sculptures, and other decorative objects.

Metaphysical properties: Dumortierite quartz is believed to have a number of metaphysical properties, including:

• It is said to promote communication, creativity, and spiritual growth.
• It is also said to be helpful for relieving stress and anxiety.