GCU - Gallium - glimpse into pastMaybe of interest/maybe you have not seen yet...
From May 2003 reference to GCU in a semiconudctor magazine
https://compoundsemiconductor.net/articles/magazine/9/5/7/1
In nature, gallium occurs in very small concentrations in rocks and ores of other metals. Most gallium is produced as a by-product of extracting aluminum from bauxite, while the remainder is extracted (principally by Dowa Mining in Japan) from by-products of zinc processing. Other leading primary producers include GEO Gallium, Pavlodar Alumina of Kazakhstan, and several companies in both Russia and China.
.....Back in 2001, Canadian company Gold Canyon Resources said it was evaluating mineral deposits in Nevada to assess the feasibility of extracting gallium as a principal product (Compound Semiconductor June 2001). CEO Robert Carrington recently said that Gold Canyon's Cordero gallium project was moving slowly at the moment, but production could start by the end of 2004 if the market picks up again.
Cheers
MAK