Thulium
Physical properties

Pure thulium metal has a bright, silvery luster, which tarnishes on exposure to air. The metal can be cut with a knife, as it has a Mohs hardness of 2 to 3; it is malleable and ductile. Thulium is ferromagnetic below 32 K, antiferromagnetic between 32 and 56 K, and paramagnetic above 56 K.

Thulium has two major allotropes: the tetragonal α-Tm and the more stable hexagonal β-Tm.
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