haruldane metall, keemiline element järjenumbriga 21

grey or whitish, or both, patch, sheet or layer of cloud which almost always has dark parts, composed of tessellations, rounded masses, rolls, etc., which are non-fibrous (except for virga) and which may or may not be merged; most of the regularly arranged small elements have an apparent width of more than five degrees

keemiline element, kollaka läikega hõbejas pehme metall, sulamistemperatuur 1541 ºC, tihedus 2,985 Mg/m3, a rare soft silvery metallic element belonging to group 3 (formerly IIIA) of the periodic table; a.n. 21; r.a.m. 44.956; r.d. 2.989 (alpha form), 3.19 (beta form); m.p. 1541°C; b.p. 2831°C