The hydrated calcium aluminum silicate, prehnite, was named after the Dutch mineralogist and military commander Colonel Hendrik Von Prehn in 1788, and it is widely believed that this was the first instance of a new mineral being named in someone’s honor.

The vast majority of material possesses a yellowish-green coloration that is somewhat pale, but brighter specimens with a similar hue may also be encountered. Pink and blue prehnites are extremely rare, while orange crystals have recently been discovered within South Africa’s manganese mining fields.

Most prehnite is too translucent to be faceted, and is instead usually fashioned into cabochons, beads and carvings. As a material with a slightly less than ideal overall durability, such cutting styles also offer a certain degree of protection against scratching and chipping.