Mtorolite is also known as matorodite, matorolite, emerald chyrsoprase, and, most accurately, chrome chalcedony, as well as under a trade name that starts with the word in Spanish for "water" and ends with "prase." It is indeed chalcedony which has been colored green by interaction with chromium (chrysoprase is chalcedony that has been colored by interaction with nickel).  This is the only producing locale in the world, so it is quite rare. The people in Zimbabwe call this "mtorolite," so we do as well. That's pronounced "muh-too-row-light."
It often forms in plates like this one. One side of this plate has been expertly polished, with attractive divots from the natural etching in the material, while the other side is left natural. 
You will receive the exact specimen pictured here 
Weight-88 grams 
Size-1.5 inches