You could buy grinding machines. You could even ruin your blender. Instead...
Go find an iron or steel plate any size, but 18 inches by 18 inches is fine. Hardware store> Junk yard? Eighteen inches is about 40 cm.
A good old hammer. A geopick adds to the fun... but certainly not necessary. Estwing makes the standard.
Then bang on your mineral! That SIMPLE? NO!
SAFETY. A geopick has a flat end like a square hammer surface and a pick end. DO NOT USE THE PICK END... stuff will go flying!
A geopick also has edges, the points of the square, which the geologist grinds ff to avoind it breaking off and flying into his or her eyes. USE A REGULAR HAMMER. A small Sledge Hammer useable one handed is best.
SAFETY!!!! EYE SHIELDS!!!
FIRST BANGS, cover the sample with an expendable piece of cloth to keep chunks from flying.
As chunks get down to sand size you can grind them with your hammer... for Better Results I recommend a mortar and pestle. Steel will add iron filings. Pharmacy Ceramic is best, but expensive, Marble is too soft and you will have calcite impurities hard to remove except with dilute HCl... hydrochloric acid. So use steel if you can and the magnet technique to purify.
NOTE... for each mineral you powder, make sure the iron plate is not contaminated with your previously-made powder!
QUARTZ goes flying! ALWAYS BUST IT UP UNDER A CLOTH! OBSIDIAN IS VERY DANGEROUS and should not be used in powdered form. MICRO GLASS SHARDS CAN KILL!
QUARTZ INCLUDES... smokey, rutilated, milky, clear varieties, citrine, amethyst, carnelian, agate and more ... All Silicon Dioxide. The colors vary due to minute amounts, very minute amounts of trace elements, or air bubbles, or small inclusions of other minerals. . Some crystal healers believe that color is important, some don't. I lean towards the DON'T camp. Your choice.
Keep your powders in lead free small glass bottles with screw on plastic covers. Keep in a dry environment before use. .
Remember to use a Saran wrapped magnet to remove iron filings which occur in the breaking.
AVOID using poisonous Minerals. Incl Arsenite, Uraninite, Cinnabar/Mercury, Galena/Lead, Asbestos.