Macdonaldite is a rare barium silicate mineral with a chemical formula of BaCa4 Si16 O36 (OH)2 ·10H2 O.[7] Macdonaldite was first described in 1965 and named for Gordon A. Macdonald (1911–1978) an American volcanologist at the University of Hawaii .[7]
Macdonaldite crystallises in the orthorhombic system. Macdonaldite is anisotropic with low relief.[8]
Macdonaldite appears as veins and fracture coatings in a sanbornite and quartz bearing metamorphic rock . Macdonaldite was first described in 1965 for an occurrence near the Big Creek-Rush Creek area in Fresno County, California . It has also been reported from Mariposa and Tulare counties in California.[4] [7] It has also been reported from a quarry in San Venanzo , Umbria , Italy.[4]
References
^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols" . Mineralogical Magazine . 85 (3): 291–320. Bibcode :2021MinM...85..291W . doi :10.1180/mgm.2021.43 . S2CID 235729616 .
^ Mineralienatlas
^ "Macdonaldite at webmineral.com" .
^ a b c "Macdonaldite at mindat.org" .
^ "Macdonaldite" .
^ Handbook of Mineralogy
^ a b c Alfors, J.T., Stinson, M.C., Matthews, R.A., and Pabst, A. (1965) Seven new barium minerals from eastern Fresno County, California. American Mineralogist, 50, 314–340.
^ Bloss, F.D. (1999) Optical Crystallography. Mineralogical Society of America, 5, 161–163.