Pure amethyst is a variety of quartz, also known as silicon dioxide, which has the formula
SiO2. So, the number of protons, neutrons, and electrons in 1 molecule of amethyst would be the sum of the protons, neutrons, and electrons for 1 atom of silicon and 2 atoms of oxygen.
1 atom of silicon has 14 protons, 14 neutrons (in its most abundant isotope, silicon-14), and 14 electrons.
1 atom of oxygen has 8 protons, 8 neutrons (in its most stable isotope, oxygen-16), and 8 electrons.
So, 1 molecule of SiO2 would have 14+2×8=30 protons , 14+2×8=30 neutrons, and 14+2×8=30 electrons