Angled Front Face Rectangle Acrylic Base 11/16 inch thick x 2 1/2 inch wide x 2 1/2 deep (bottom face) and 1 7/8 (top face), $10.
ANGLG
Top face for mounting mineral is 2 1/2 inch wide and 1 7/8 inch deep. Overall footprint is 2 1/2 inch x 2 1/2 deep. Angled face 3/16 inch x 2 1/2 wide allows room for labeling.