Yttrialite [SEP] named after
Yttrialite
Yttrialite or Yttrialite-(Y) is a rare yttrium thorium sorosilicate mineral with formula: (Y,Th)SiO. It forms green to orange yellow masses with conchoidal fracture. It crystallizes in the monoclinic-prismatic crystal system. It has a Mohs hardness of 5 to 5.5 and a specific gravity of 4.58. It is highly radioactive due to the thorium content. 
It is found associated with gadolinite. It was first described in 1889 for an occurrence in the Rode Ranch pegmatite on Baringer Hill, Llano County, Texas. It has
William Niven
William Niven (2 October 1850 – 2 June 1937) was a mineralogist and archeologist noted for his discovery of the minerals yttrialite, thorogummite, aguilarite and nivenite (named after him), as well as a set of controversial tablets. Originally from Scotland, Niven came to the United States in 1879, where he became heavily involved in mineralogy and mining.
Mineral discoveries.
Niven's first major contribution to mineralogy occurred in 1889 while he was on an expedition to Llano County, Texas, on behalf