mat4 is used at run time in 3 crates. It's used only as a dev dependency in 3 crates.

Depender (with downloads and own rev deps) mat4 version
2 specs_camera ^0.2
3 specs_transform ^0.2
gmath ^0.2
1 specs_sprite dev ^0.2
assets dev ^0.2
2 gl_helpers dev ^0.2