Samuelsonite is a complex mineral that is found near North Groton, Grafton County, New Hampshire, US.

Additionally, it is most commonly found as a secondary mineral in granite pegmatite.

Samuelsonite is named after Peter B. Samuelson,[2] a prospector from Rumney, New Hampshire.

The mineral has a pale yellow color and has a hardness of 5 on Mohs scale.

[6] Samuelsonite has biaxial birefringence (trirefringence), meaning when light passes through the optic axis it is split into two rays due to the difference in refractive index of the ray with parallel polarized light compared to the ray with perpendicular polarized light.