/usr/share/gwyddion/glmaterials/Pewter is in gwyddion-common 2.47-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 | Gwyddion resource GwyGLMaterial
0.105882 0.058824 0.113725 1.0
0.427451 0.470588 0.541176 1.0
0.333333 0.333333 0.521569 1.0
0.0 0.0 0.0 1.0
0.076923
|