Brookite mineral

Brookite is the TiO2 mineral species listed by IMA-CNMNC in September 2026 with grandfathered status G and original-description year 1825. That year is not an IMA approval identifier. It is distinct from the rutile and anatase mineral species, from elemental titanium and from unspecified manufactured TiO2 particles. Liu and colleagues studied natural brookite from Magnet Cove, Arkansas, USA, obtained as specimen 8115 from the University of California, Berkeley Earth and Planetary Science collection. Selected black crystals were cleaned with 1 mol/L nitric acid, washed, dried, crushed and ground. Ambient powder XRD and Rietveld fitting support the brookite phase assignment; the subsequent high-pressure experiment is not a microbial assay. Two EDS locations on one ground particle yielded mean reported abundances of O 38.64, Ti 59.23 and Nb 2.13 weight percent. These are localized analyses, not a bulk ore grade, a representative mine inventory or evidence of a chemically pure endmember. Figure S2 compares powder before and after pressing near 8 MPa and supports no apparent phase change during that preparation step. Later compression in a diamond-anvil cell produces pressure- and medium-dependent TiO2 phase mixtures; the source explicitly treats the phase-content diagrams as kinetic, non-equilibrium observations. Its baddeleyite terminology refers to a TiO2 structural polymorph, not formation of the zirconium mineral species ZrO2. No microbial mechanism, titanium extraction yield, industrial recovery or constituent-derived criticality is asserted by this identity and natural-specimen record.

Record source: data/records/brookite.yaml