Gift from Tony Steede – thanks Tony!. Analyzed find. MOB coll. Stereo pair. Judging from the scarcity of Mindat posts for this mineral, it appears to be very rare. Hence, even though this photo isn’t very good - it barely works even in stereo – it may be worth posting. This is the best I can do with my set-up. The xls are just very tiny. To the naked eye (through the scope), the xls appear prismatic and hexagonal. That may seem surprising for a serpentine group mineral, but Tony Steede did EDS and Malcolm Back did XRD confirming kellyite. (This find is described in a copy of a page from a CMMA Micronews Bulletin which I have dated as March 2006. However, there is no date on the article itself and I am unable to find the actual bulletin.) The xls appear to be not quite colorless – but more yellowish than the brownish shade in the photo. (At this magnification, I get a great deal of chromatic aberration and have to resort to brute force to get rid of it. That’s not always possible without affecting the color of the material of interest.) The very small size of the specimen precludes determination of the environment. The only other recognizable mineral is natrolite. Tony mentions sphalerite, aegirine and ancylite. Modified by CombineZP. — Photo: Modris Baum · CC0
Kellyite
Kellyite is an IMA-recognized mineral species in the silicate class, with the chemical formula (Mn²⁺,Mg,Al)₃(Si,Al)₂O₅(OH)₄.
It crystallizes in the hexagonal crystal system. It is a member of the Serpentine, Clay structural group.
Key properties: specific gravity 3.07; optically biaxial.
IMA symbol Kly, IMA status: approved, named in 1974.
Found in banded Ca-Mn carbonate-rich rocks (Bald Knob mine, North Carolina, USA); in an intrusive alkalic gabbro-syenite complex (Mont Saint-Hilaire, Canada).
It is found associated with Kutnohorite, galaxite, jacobsite, manganoan chlorite, alleghanyite, sonolite (Bald Knob mine, North Carolina, USA); aegirine, analcime, calcite, catapleiite.
The mineral was named to honor Professor William Crowe Kelly (1929{), geologist, of the University of Michigan, Ann Arbor, Michigan, USA.