16.12.01: Alexandrite
- Page ID
- 4339
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)| Alexandrite | |
|---|---|
| Chemical composition | Al2(BeO4)Beryllium aluminum oxide |
| Crystal system | Orthorhombic |
| Habit | Tabular, pseudo-hexagonal |
| Cleavage | Imperfect prismatic |
| Fracture | Weak, conchoidal |
| Hardness | 8.5 |
| Optic nature | Biaxial + |
| Refractive index | 1.744 - 1.755 |
| Birefringence | 0.009 |
| Dispersion | Low, 0.014 |
| Specific gravity | 3.70 - 3.72 |
| Lustre | Bright vitreous |
| Pleochroism | Strong |
Figure \(\PageIndex{1}\): Adularescent Alexandrite 26.74 carats
Tunduru, Ruvuma, Ruvuma Region, Tanzania
Figure \(\PageIndex{2}\): Alexandrite from Hematia, Minas Gerais, Brazil
Viewed in daylight (greenish) and with LWUV (reddish)
Figure \(\PageIndex{3}\): Alexandrite crystals photographed in candle light and daylight
Yekaterinburg, Russia
Alexandrite is a phenomenal variety of the mineral chrysoberyl. Because of the trace amounts of the chromophores vanadium and chromium, alexandrite appears different colors depending on whether it is viewed in natural or incandescent light. In daylight, the stone appears to be green; in artificial light it appears to be raspberry red. It was originally discovered in the Ural Mountains in 1830 on the birthday of Czar Alexander of Russia. Another extraordinary coincidence was that the national colors of Russia were red and green. Today, alexandrite is found in Russia, Brazil, India and to a lesser extent in Africa. Alexandrite has long been associated with great luck and prosperity.
Inclusion Images
Figure \(\PageIndex{4}\): Liquid veil and twinning resembling a venetian blind effect
Courtesy of Barbra Voltaire
Additional Phenomena
| Alexandrite image gallery |
- Cat's Eye
|
Figure \(\PageIndex{5}\): Cat's eye Alexandrite under daylight |
Figure \(\PageIndex{6}\): Cat's eye Alexandrite under incandescent light; Photo courtesy of The Gem Trader |
G&G Articles on Alexandrite 1934-1980
The GIA has published all the G&G's from 1934 until 1980 online. The organization of the list by subject was done by Joseph Gill.
- Spring 1949, The Origin of Alexandrite Color Change, p. 143, 3pp.
- Spring 1959, A 45 ct., a 12 ct., and a 50 ct. alexandrite, p. 264, 1p.
- Winter 1963, A cat's-eye alexandrite, p. 104, 2pp.
- Fall 1964, Synthetic alexandrite made, p. 216, 1p.
- Winter 1974, A new synthetic alexandrite by the Czochralski Method, p. 367, 3pp.
- Fall 1976, Alexandrite from Lake Manyara, Tanzania, by Gübelin, p. 203, 11 pp., with bibliography
- Fall 1976, African alexandrites?, p. 211, 3pp.
- Spring 1979, Natural & Synthetic Alexandrites, p. 148, 1p.