Tourmalinated Quartz
Tourmalinated Quartz is quartz that contains tourmaline as inclusions. Many specimens appear to have needle-like or fibrous black lines, and their appeal lies in the contrast between these inclusions and the clarity of the quartz.
A distinctive stone featuring the clarity of quartz combined with the linear inclusions of tourmaline.
Basic Information
| English Name | Tourmalinated Quartz |
|---|---|
| Japanese Name | Denkiseki-iri Suisho (Tourmaline-included Quartz) |
| Chemical Composition | SiO2 / NaFe3Al6(BO3)3Si6O18(OH)4 (for Schorl) |
| Hardness | 7 / 7.5 |
| Specific Gravity | 2.65 / 3.3 |
| Transparency | Transparent to translucent |
Characteristics & Variations
- Main types of included tourmaline: Besides schorl (iron tourmaline) and dravite, inclusions can also include elbaite (green tourmaline), indicolite, and in rare cases, watermelon tourmaline.
- Domestic (Japanese) specimens: In Japan, quartz containing dravite from the Otome mine in Yamanashi Prefecture is well-known and locally referred to as "Ochi-iri suisho."
Varieties
- Tourmalinated Quartz Cat's Eye: When extremely fine tourmaline inclusions are arranged densely in parallel, a chatoyancy (light-ray effect) can occur.
Locality, Aliases, Treatments, & Similar Stones
Trade Names:
- Sapphire Quartz: A trade name derived from sapphire (the name only), used for quartz containing indicolite that gives the stone an overall blue appearance. It is also known as blue quartz.
Treatments:
- Impregnation: If the quartz has many cracks, it may be treated with oil or resin to make them less visible.
Similar Stones:
Note: Specimens with high inclusion levels are prone to surface and internal cracking and may have undergone impregnation treatment. Additionally, since other minerals can look like black lines similar to tourmaline, always verify the details (treatment status and type of inclusions) when sourcing or gem-identifying.