Olivine is one of many low value minerals that are magma-safe, and can be used for floodgates and mechanisms used for the controlling of magma. It is also one of the few minerals that contains native platinum (the other being magnetite).
Items built using olivine will be dark green.
 In the real world
Olivine is a magnesium iron silicate mineral with the chemical formula (Mg,Fe)2SiO4. It is defined by its bright green color. Gem-quality examples of the mineral are called peridot.
It is also the most common rock in the world, taking up an estimated 80% of the world's volume, of course most of this is in the mantle 7km underground in the sea and an average 35km beneath the continent. Even dwarves can't dig that far down.
[INORGANIC:OLIVINE] [USE_MATERIAL_TEMPLATE:STONE_TEMPLATE] [STATE_NAME_ADJ:ALL_SOLID:olivine][DISPLAY_COLOR:2:7:0][TILE:'%'] [ENVIRONMENT_SPEC:GABBRO:CLUSTER:100] [IS_STONE] [MELTING_POINT:13168] [SOLID_DENSITY:3320]