flatness  

   0.5%(max)

 thickness   

   +/-1mm

  air hole

   diameter:1.5mm/pc(max), 2pcs/M2(max)  

     impurity     

undistinctness by visual keep 1m distance

 desiccation and compressive strength

 70.9MPA(min)

water absorption       

    zero 0

  bending strength   

 43.5Mpa(min)

 volume  density 

   2.55G/CM3

  glossiness

  96

 mohs hardness

     6.0

acid fastness  

K:0.13%,appearance no change when dipping

                         in 1.0% vitriol for 650 hour

resistance to alkali 

 K:0.08%,appearance no change when dipping

                in 1.0% sodium hydroxide for 650 hour

  radioactivity 

 no radioactivity,suitable for class A decoration