Bi-colour Mushroom Tourmaline. From: Mogok, Pyin-Oo-Lwin District, Mandalay Division, Myanmar
Credit: Anton Watzl
What an awesome bi-colour mushroom tourmaline! One of a kind!
The tourmaline group is the most important of the cyclosilicates subclass with about fifteen known species of which the most common are the schorl, the dravite, the elbaite but also the liddicoatite, the uvite, etc... Its name comes from the Sinhalese turamali which literally means "stone which attracts ashes" because its crystals provoked a phenomenon formerly incomprehensible, heated above a fireplace, they attracted the ashes. Under the effect of heat the crystals are charged electrically : it is the pyroelectricity feature that is responsible for this phenomenon known since Antiquity.
Tourmalines are found in granitic pegmatites, in pneumatolytic veins, and also in some granites. It may also occur in metamorphic rocks that have undergone metasomatism. It generally crystallizes in elongated and striated prisms with trigonal sections. The crystals can be very colorful : colorless and transparent, brown to black (ferromagnesian tourmalines : schorl and dravite), pink, red, blue or green (lithic tourmalines : elbaite or liddicoatite), multicolored crystals that can be frequent on some deposits. It is a mineral that alters in phyllosilicates (micas and chlorites) which can partially pseudomorph.
Hardness: 7 - 7.5
Crystal System: Hexagonal