What is Rainbow Lattice Sunstone?

Rainbow Lattice

A rainbow captured in a gemstone

Sunstone is a beautiful gem formed when reflective crystals grow inside crystals of Plagioclase. Because the reflective crystals grow aligned with the host crystal they all face the same direction and show a brilliant flash when the angle is just right.

Moonstone is a beautiful gem formed when an Alkali Feldspar cools and separates into two types of Feldspar - Albite and Orthoclase. The fine scale layering cause the “moonstone” light effect known as Adularescence.

Rainbow Lattice Sunstone in the rough

Rainbow Lattice is something else again....

For starters, the host mineral is nearly pure Orthoclase, chemically far removed from ‘normal’ Moonstone or Sunstone. Yet it is a Moonstone that also has Sunstone inclusions.

But that’s not all - Rainbow Lattice Sunstone has two types of Sunstone - laths and triangles of magnetite (steely grey), and hexagonal plates of hematite (orange).

The real magic is the Rainbow! The surface of the magnetite laths exhibits thin film interference, splitting light into the full spectrum of colors…

Literally a rainbow trapped in the stone.

Rainbow Lattice Sunstone showing Moonstone and Magnetite laths

Nature is working against us here. These gemstones grew under extreme heat and pressure from very old rocks. Crystals grew but most did not survive deformation; the host rock is highly fractured and conditions had to be just right for the haematite and magnetite to grow. The rainbow only forms when the stone is weathered, fractured and exposed to the elements. We find the material in a brief window of time as it is recycled by erosion and returned to the soil.

But the results are astounding…