A matrix specimen with several outstanding yellow crystals of rare Sr mineral strontiojoaquinite on crossite matrix. California field collector & mineral dealer Charles (Chuck) Trantham in the 1970s originally gave this source locality the unofficial name of the "M.T. Jeannes Pit #1". Sometime later (1980s?) an official claim was made of mineral rights with U.S. BLM, and the claimant named this source locality: The Junilla Mine. The old name of this locality on the label likely dates this specimen as found in the 1970s. Ex. William Henderson collection. Ex. Erich Laskowski collection (USA). — Photo: David Hospital · CC BY 4.0
Strontiojoaquinite
Strontiojoaquinite is an IMA-recognized mineral species in the silicate class, with the chemical formula (Na,Fe)₂Ba₂Sr₂Ti₂(SiO₃)₈(O,OH)₂·H₂O.
It crystallizes in the orthorhombic crystal system. It is a member of the Joaquinite structural group.
Key properties: Mohs hardness 5.5; specific gravity 3.68; optically biaxial.
IMA symbol Sjq, IMA status: approved, named in 1979.
Found in a metamorphosed and metasomatized basalt lens in serpentinite (Mina Numero Uno, California, USA); in veins cutting metagraywacke (prospect, San Benito Co., California, USA).
It is found associated with Joaquinite-(Ce), neptunite, natrolite, albite, actinolite, crossite, benitoite, analcime.
The name refers to its strontium content and its relation to joaquinite in contrast to strontio-ortho joaquinite.