Skip to main content
Geosciences LibreTexts

16.27: Clinohumite

  • Page ID
  • \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)

    Chemical composition Magnesium silicate
    Hardness 6
    Optic nature Biaxial +
    Refractive index 1.628 - 1.674
    Birefringence 0.024 - 0.041
    Specific gravity ~ 3.21
    Lustre Vitreous
    Pleochroism Strongly trichroic

    SWUV: strong orange yellow
    LWUV: generally inert

    Figure \(\PageIndex{1}\): A 9.45 ct brownish orange clinohumite tested at the Gem Testing Laboratory, Jaipur.

    Clinohumite is a member of the humite group. As a gemstone it is rare, but some cut stones are reported. The given below details are (largely) abstracted from Journal of Gemmology, 2007, 30, 5/6, 303-306 "A remarkably large clinohumite".





    Bright yellow-orange color resembling some hessonite and spessartine garnets.
    Cause of color: Mn




    Clinohumite has a biaxial optic character with a positive optic sign.
    The refractive index range of clinohumite: nα = 1.628 - 1.638, nβ = 1.641 - 1.654, nγ = 1.662 - 1.674.
    The maximum birefringence ranges from 0.024 to 0.041.

    For a specific stone tested (9.45 ct. brownish orange clinohumite tested at the Gem Testing Laboratory, Jaipur): R.I.: 1.646-1.670, birefringence: 0.024.


    Strong trichroism: yellow, orange and brownish yellow.

    Specific gravity

    S.G.: ~ 3.21


    Figure \(\PageIndex{2}\): Diffraction spectrum

    Brownish-orange clinohumite.
    General cut-off till 430nm (from 400nm).


    SWUV: strong orange-yellow;
    LWUV: generally inert


    Inclusions: Strong color and growth zoning, flat parallel reflective planes, fluid-like inclusions similar to trichites in tourmaline. Such liquid inclusions along with doubling appear very much like tourmaline; tube like inclusions; sometimes swirly zones.


    Geographical occurrence: Gem quality Clinohumite is known to occur in two important localities - The Pamir mountains (at Kukh-i-lal, Sumdzin and Changin); in Tajikistan in association with spinel and in the Taymyr region (Basin of Kotui river) in Siberia; Also in Mahenge, Tanzania.


    • G.Choudhary and Chaman Golecha, A remarkably large Clinohumite, Journal of Gemmology, 2007, 30, 5/6, pp 303-306
    • Henn, U., Hyrsl, J., and Milisenda, C.C., Gem Quality clinohumite from Tajikistan and the Taymyr region, Northern Siberia. Journal of Gemmology, 27(6), 335-9
    • Hyrsl, J., 2001. Gem News International. Spinel with clinohumite from Mahenge, Tanzania, Gems and Gemology, 37(2), 144-5
    • Laurs, B.M., and Quinn, E.P., 2004. Gem News International. Clinohumite from Mahenge, Tanzania. Gems and Gemology, 40(4), 337-8
    • Gems Their Sources, Descriptions and Identification 4th Edition (1990) - Robert Webster (6th ed.)
    • Colour Encyclopedia - J.E. Arem ISBN 0412989115
    • Introduction to Optical Mineralogy 3rd edition (2003), Prof. W.D. Nesse

    This page titled 16.27: Clinohumite is shared under a CC BY-NC-SA 2.5 license and was authored, remixed, and/or curated by gemology via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.

    • Was this article helpful?