<mujoco>
  <asset>
    <material name="block_mat" specular="0" shininess="0.5" reflectance="0" rgba="1 0 0 1"/>
  </asset>
  <worldbody>
    <body>
      <geom type="box" size="0.02 0.02 0.02" rgba="1.0 0.0 0.0 1.0" material="block_mat" condim="4" />
      <joint type="free"/>
    </body>
  </worldbody>
</mujoco>