A light grey or white hydrated basic phosphate of sodium, potassium, calcium, and aluminium, (Na,K)CaAl₆(PO₄)₄(OH)₉·3H₂O, crystallizing in the tetragonal system and occurring as finely fibrous crusts and spherules.
Origin
1930s. From the name of F. T. Millis, of Lehi, Utah + -ite.
Definition of millisite in US English:
millisite
nounˈmɪlɪsʌɪt
Mineralogy
A light grey or white hydrated basic phosphate of sodium, potassium, calcium, and aluminium, (Na,K)CaAl₆(PO₄)₄(OH)₉·3H₂O, crystallizing in the tetragonal system and occurring as finely fibrous crusts and spherules.
Origin
1930s. From the name of F. T. Millis, of Lehi, Utah + -ite.