Auction Win: Tobermorite after Hydroxyllestadite

Locality: Crestmore quarries, Crestmore, Jurupa Valley, Riverside County, California, USA

Size: Miniature - 5.5 × 2.1 × 1.2 cm

Hydroxylellestadite is a hexagonal calcium silicate-sulfate hydroxide mineral with formula Ca5(SiO4)1.5(SO4)1.5(OH). It was first introduced by McConnell in 1937 from Crestmore, California, and its name comes from Ellestadite.

Tobermorite is a calcium silicate hydrate mineral with formula Ca4Si6O17(H2O)2 · (Ca · 3H2O). It was named for Tobermory on the Isle of Mull, Scotland, its discovery locality, and its species was later redefined by IMA in 2014.

Crestmore quarries in Jurupa Valley, Riverside County, California, are one of the classic mineral localities of southern California, worked on the east end of the Jurupa Mountains and closely associated with the Crestmore limestone bodies and their contact-metamorphic rocks. The site is famous for an exceptionally diverse suite of nearly 150 mineral species, including many first recognized there, formed by high-temperature metasomatism where intrusive quartz monzonite and related rocks altered the local limestones into marble, skarn, and pegmatitic assemblages. Quarrying here continued until 1986, and specimens from Crestmore remain highly sought by collectors for their historic importance and extraordinary species list.