Count Material with equal Text in the same column

[Daniel1908]

Hello Together, 

I want to count only the Material Numbers which got the same Description Text in the same column. 

Any Ideas how to create the formula?

Kind Regards,
Daniel

[tresB]

Example?

[Daniel1908]

In the below case I only want to count Srews and Pliers because they have more than one entry for the description. 
I do not want to count the Material Number which have the description once.