From the case:
Gadolinium (photo)
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Pure (99.95%) amorphous gadolinium, ~12 grams, 2 × 1.5 × 0.5 cm, cast in acrylic glass.
Author: Jurii. See case discussion for full attribution.
Case Discussion
Attribution
Author: Jurii
Original file: https://commons.wikimedia.org/wiki/File:Gadolinium-2.jpg
Modifications: replaced background
License: Creative Commons Attribution 3.0 Unported license