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Foundation 9 of 12
Revelation 21:20

Topaz

τοπάζιον

Strongly pleochroic: its color shifts with the angle of the light passing through.

Mineralogy
Greek name
topazion (τοπάζιον)
Modern identification
Topaz
Chemical formula
Al₂SiO₄(F,OH)₂
Crystal system
Orthorhombic
Optical class
Biaxial (+)
Birefringence (Δn)
0.008–0.010
Refractive indices
1.609–1.643
Color / appearance
Colorless, yellow, blue, pink

Perfect basal cleavage; strongly pleochroic in colored varieties.

The light between

Topaz is anisotropic: enter it with a single ray of light and it leaves as two, split apart by the crystal's inner order. This is birefringence, the same property shared by every one of the twelve foundation stones, and by none of the cubic stones left out of the list.

In the high-priestly breastplate of Exodus 28, this position held Amethyst in the Septuagint reckoning.

Hold the light in your hand

The Revelation Stones collection brings each foundation stone into the room with you, and the Light Between research explains what you are looking at.