Proustite is a sulfosalt mineral consisiting of silver sulfarsenide. This specimen was found in Nieder Schlema Germany probably over a hundred years ago (as is typical of pieces from this locality). The first pic shows the cherry crimson color of the crystal with an LED backlight, the second pic is not backlit.The primary crystal is 3 cm long by 1.2 cm wide. There is one repair to this primary crystal that is imperceptible.