Pure amethyst is a variety of quartz, also known as silicon dioxide, which has the formula #SiO_2#.
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 #SiO_2# would have #14+2xx8=30# protons, #14+2xx8=30# neutrons, and #14+2xx8=30# electrons.