AllMineralsRock
Alexandrite
Alexandrite is an uncommon gemstone composed of beryllium aluminate with chromium. [1]
Alexandrite: Quick Facts and Characteristics
Some quick facts for Alexandrite:- Transparency: Alexandrite can be opaque, translucent or transparent.
- Crystallography: In terms of crystallography, alexandrite is orthorhombic.
- Luster: In terms of luster, alexandrite is vitreous (glassy).
- Streak: Alexandrite streaks colorless.
- Hardness: Alexandrite's hardness is 8.5 on the Moh's scale.
- Specific Gravity: Alexandrite's specific gravity ranges from 3.68 to 3.8.
Alexandrite: Background and Summary
Alexandrite is a rare and highly valued mineral that belongs to the chrysoberyl family. It is known for its unique color-changing properties, which can range from green or blue-green in daylight to purplish-red in incandescent light. This phenomenon is called pleochroism, and it is caused by the mineral's composition, which includes traces of chromium.Alexandrite is a relatively hard mineral, with a Mohs hardness rating of 8.5, which makes it durable and suitable for use in jewelry. It is also relatively rare, and high-quality specimens can be quite expensive. The most valuable alexandrite is found in Russia, but it can also be found in Sri Lanka, Brazil, and other parts of the world.
To identify alexandrite, one can look for its unique color-changing properties, as well as its hardness and crystal structure. It has a distinct tetragonal shape, and it often has a yellow-green or brownish-yellow color in its natural state. However, when viewed under the right conditions, such as in incandescent light, it can exhibit a striking purplish-red hue.
Alexandrite has a variety of uses, but its most common application is in jewelry. It is prized for its color-changing properties, which make it a unique and interesting gemstone. It is also used in watchmaking and other precision instruments, as well as in some scientific equipment.
Alexandrite: Table of Properties
| Attribute | Alexandrite (src) |
|---|---|
| Transparency | transparent, translucent, opaque |
| Chemical Formula | BeAl2O4 |
| Chemical Composition | beryllium aluminate with chromium |
| Specific Gravity | 3.68, 3.8 |
| Hardness | 8.5 |
| Streak | colorless |
| Crystallography | orthorhombic |
| Refractive Index | 1.745, 1.759 |
| Hydrous | No |
| Colors | common: green sometimes: red, blue, purple less common: gray, pale, pink, violet, yellow, multicolor |
| Fracture | 1: 1 |
Alexandrite: FAQ
Q: Is alexandrite a birthstone?A: Yes, alexandrite is one of the birthstones for the month of June.
Q: How rare is alexandrite?
A: Alexandrite is relatively rare, and high-quality specimens can be quite expensive.
Q: Can alexandrite be treated or enhanced?
A: Some alexandrite may be treated or enhanced to improve its color or clarity, but this can affect its value.
Q: How should I care for my alexandrite jewelry?
A: Alexandrite is a relatively hard mineral, but it should still be treated with care. Avoid exposing it to harsh chemicals or extreme temperatures, and clean it gently with a soft cloth and mild soap.
Sources
- Gemological Institute of America. "Alexandrite." https://www.gia.edu/alexandrite- Smithsonian Institution. "Alexandrite." https://geogallery.si.edu/10002031/alexandrite
- Alexandrite: https://en.wikipedia.org/wiki/Chrysoberyl#Alexandrite
Previous Mineral: acanthite Next Mineral: andalusite