Brøgger (1879) gave a crystallographic description of a black mineral from Urstad without chemical analysis. He thought it to be identical with aeschynite (From Miask, which later was named aeschynite-(Ce)). In Brøgger (1906) the mineral were described in detail, and gave it the name Blomstrandine. He states on p. 104 the that aeschynite from Miask is a Cerium-Aeschynit and that the blomstrandine from Hitterö was a "Yttrium-Aeschynit".
A part of a crystal weighing 3kg and chunks up to 20 kg has been noted.
Habit:
Platy after {010}, with the dominant form {010}, {130}, {001}. Forms also observed: {110}, {120}, {111}, {101}, [001}
Colour:
Brownish black, metamict with thin brownish alteration
Urstad Feldspar Mine, Hidra, Flekkefjord, Agder, Norway