Brammallite is a sodium-rich analogue of illite. First described in 1943 for an occurrence in Llandybie, Wales, it was named for British geologist and mineralogist Alfred Brammall (1879–1954).
{{Infobox mineral | name = Brammallite | category = Phyllosilicate minerals | group = Mica group, dioctahedral mica group | image = | caption = | formula = (Na,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2·(H2O)] | IMAsymbol=Bmr | molweight = | color = White | habit = Earthy clay like | system = Monoclinic | class = Prismatic (2/m) (same H-M symbol) | twinning = | cleavage = Perfect on {001} | fracture = | tenacity = | mohs = – 3 | luster = Dull, earthy | polish = | refractive = nα = 1.535 – 1.570 nβ = 1.555 – 1.600 nγ = 1.565 – 1.605 | opticalprop = Biaxial (−) 2V: Measured: 5° to 25° | birefringence = δ = 0.030 – 0.035 | dispersion = | pleochroism = | fluorescence= | absorption = | streak = White | gravity = 2.83 – 2.88 | density = | melt = | fusibility = | diagnostic = | solubility = | diaphaneity = Translucent | other = | references = }}
Brammallite is a sodium-rich analogue of illite. First described in 1943 for an occurrence in Llandybie, Wales, it was named for British geologist and mineralogist Alfred Brammall (1879–1954).
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).