If you crush crystals to powder you will contaminate your sample with the crushing equipment. How much depends on material properties of both the crystals and the equipment. To what extend this influences your sample depends on what properties you are interested in.
The big difference in your results is regards to the hardness of spatula material. Every time you expose the object with pressure you will also harm the masher.
The problem, materials and options sholud be decribed in details.