/usr/share/gwyddion/glmaterials/Silver 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
0.19225 0.19225 0.19225 1.0
0.50754 0.50754 0.50754 1.0
0.508273 0.508273 0.508273 1.0
0.0 0.0 0.0 1.0
0.4
|