Dalyite

Dalyite is a rare accessory zirconium silicate. Compared to other zirconium silicates, it is the most saturated with silica and is characteristic of quartz-containing alkaline rocks.

Dalyite is usually colorless, sometimes brownish or slightly violet. It has a hardness of 7.5 and a white streak. Clear cleavage noted. It often forms aggregates of isometric crystals.

It first described in a block of alkali granite from Ascension Island (Van Tassel, 1952). Dalyite named after Reginald Aldworth Daly (1871-1957), an American petrologist who studied the geology of Ascension Island.