Pyroxene Visible Spectra (generally 350 - 2500 nm)

polarizations: (a = alpha direction; b = beta direction; g = gamma direction) 

Pictures of pyroxenes showing the pleochroism

        Enstatite polarized parallel to the c-axis; two crystals, one from Tanzania, the other from Myanmar
        Enstatite polairzed parallel to the b-axis
        Both, compared side-by-side.                           T

Images of representative orthopyroxene spectra

Synthetic orthopyroxenes containing various transition elements.

Synthetic clinopyroxene containing various transition elements.

Synthetic protopyroxene containing vanadium.

Images of representative clinopyroxene spectra

Special Clinopyroxene Topics:



    Spodumene comes in various colors. Pink ones are known as kunzite. Green, chromium-containing ones are known as hiddenite. Then can also occur naturally green in chromium-free spodumenes due to radiation exposure. Such matrial usually fades rapidly to pink when exposed to bright light.

    Irradiated Kunzite

    When irradiated, kunzite will turn green. Both natural irradiation (e.g., from the decay of naturally radioactive potassium-40) and laboratory irradiation (e.g., X-rays and gamma rays) will serve to make the color change occur.

Irrad Spod
Spodumene GRR 831 from Afghanistan irradiated with Cs-137 gamma rays

This irradiation-induced green color has been observed for many years, and has been investigated by several workers including Fred Pough

Pough F, Rogers TH (1947) Experiments in x-ray irradiation of gem stones. American Mineralogist 32, p31-43.


Hiddenite spectrum; Spodumene, CIT 11149, green hiddenite hiddenite from North Carolina, USA.  Thickness: 2.96 mm, two polarizations on the cleavage 110 face of this Cr3+-containing spodumene. 

Link to an extensive collection of references to mostly color and visible spectroscopy of pyroxenes

Link to references about the spectra of spodumene

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revised 5-Apr-2023