Sturmanite is a rare sulfate mineral with the chemical formula Ca6Fe3+2(SO4)2.5(B(OH)4)(OH)12 · 25 H2O. It crystallises in the tetragonal system and it has a Moh's hardness of 2.5. Sturmanite has a bright yellow to amber colour and falls in the ettringite group. It was named after Bozidar Darko Sturman (born 1937), Croatian-Canadian mineralogist and Curator Emeritus of Mineralogy, Royal Ontario Museum.
via Wikipedia infobox
{{Infobox mineral|name=Sturmanite|boxwidth=|boxbgcolor=|image=Sturmanite-240577.jpg|imagesize=260px|alt=|caption=Distinctive sturmanite on matrix from the N'Chwaning Mines. Size: 5.4 x 4.2 x 1.7 cm. Ex.Charlie Key Stock|category=Sulfate minerals|formula=Ca6Fe3+2(SO4)2.5[B(OH)4](OH)12 · 25 H2O| IMAsymbol = Strm|molweight=|strunz=7.DG.15|dana=32.4.4.2 |system=Trigonal |class = 3m - Ditrigonal Pyramidal |symmetry=P31c (no. 159)|unit cell=a = 11.188(9) Å, c = 21.91(7) Å|color=Bright yellow to amber|colour=|habit=Hexagonal, pyramidal, prismatic|twinning=|cleavage=Perfect {1010}|fracture=|tenacity=Brittle|mohs=2.5|luster=Vitreous, greasy|streak=Pale yellow, greenish yellow, brownish orange|diaphaneity=Transparent to translucent|gravity=1.847 (measured)
1.855 (calculated)|density=|polish=|opticalprop=Uniaxial (+/-)|refractive=|birefringence=δ = 0.002|pleochroism=|2V=|dispersion=|extinction=|length fast/slow=|fluorescence=none|absorption=|melt=|fusibility=|diagnostic=|solubility=|impurities=|alteration=|other=|prop1=|prop1text= }} Sturmanite is a rare sulfate mineral with the chemical formula Ca6Fe3+2(SO4)2.5(B(OH)4)(OH)12 · 25 H2O. It crystallises in the tetragonal system and it has a Moh's hardness of 2.5. Sturmanite has a bright yellow to amber colour and falls in the ettringite group. It was named after Bozidar Darko Sturman (born 1937), Croatian-Canadian mineralogist and Curator Emeritus of Mineralogy, Royal Ontario Museum.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).