Mookaite is a jasper. It comes from the skeletal remains of radiolaria which were microscopic protozoa that had a silica shell in the Cretaceous Era. The shells deposited in shallow water over millenia and when the water level receded and additional silicas were deposited, these bright contrasting bands of mustard-yellow and burgundy-brown mineral were produced (also comes in reds, creams, and mauves). It's a hard stone - 6.5 to 7 - and is a popular choice for men's jewelry. Bet no man describes his cuff links as "mauve" though - he probably refers to the color as "wine".