6.4 x 2.4 x 1.9 cm. Davreuxite is a very rare Mn-Al silicate found in only a few localities in Belgium. Fibrous, pearlescent, cream-colored davreuxite richly covers two sides of the sculptural, milky quartz shard. From: Ottré, Vielsalm, Stavelot Massif, Luxembourg, Wallonia, Belgium. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Davreuxite
Davreuxite is an IMA-recognized mineral species in the silicate class, with the chemical formula Mn²⁺Al₆Si₄O₁₇(OH)₂.
It crystallizes in the monoclinic crystal system (space group P2_1/m).
Key properties: Mohs hardness 2–3; specific gravity 3.3–3.38; optically biaxial.
IMA symbol Drx, grandfathered status — known before the IMA’s founding, named in 1878.
Found in quartz veins cutting Mn, Al-rich metapelites, derived from shales subjected to low-grade metamorphism.
It is found associated with Quartz, pyrophyllite, ottr¶elite, andalusite, sudoite, kaolinite, rutile, dickite (Ottr¶e, Belgium); chloritoid, hematite, chlorite (Sart-Close, Belgium).
The name refers to Charles Joseph Davreux (1800–1863), Belgian pharmacist and natural scientist, Professor of Mineralogy at the University of Liµege, Belgium.