Black Garnet

Black garnet is an opaque, jet-black to brownish-black garnet, almost always the melanite variety of andradite, often enriched in titanium. Its color comes from iron and titanium content.

With a high luster when polished, black garnet was popular in 19th-century mourning jewelry and remains a striking choice for modern dark gemstone settings.

The most titanium-rich black garnets grade into a related species called schorlomite. Black garnet is opaque rather than transparent, distinguishing it from most gem garnets.

Black garnet (melanite) forms in alkaline igneous rocks such as nepheline syenites and phonolites, and in some skarns and metamorphosed limestones, where calcium, iron, and titanium combine during crystallization.

Its titanium content links it to silica-undersaturated, alkali-rich magmas.

Notable sources include alkaline complexes in Italy (Mt. Vesuvius area), Germany (Kaiserstuhl), France, Russia, and the USA (Arkansas for schorlomite-rich material).

Black garnet is identified by its opaque black color, high (sub-adamantine) luster when polished, and isometric, singly refractive garnet character.

• Hardness: 6.5-7.
• Streak: white to grayish-brown.
• No cleavage; conchoidal fracture.

Distinguish from black tourmaline (schorl), which is doubly refractive and forms striated prismatic crystals, and from black spinel and obsidian. Black garnet's isometric dodecahedral crystal form and single refraction help confirm it.

Black garnet is faceted or cabbed for jewelry, valued for its deep black color and bright luster; it has a long history in Victorian mourning jewelry as an alternative to jet and onyx.

It has little industrial use and is mainly a gemstone and collector material; schorlomite-rich varieties are of mineralogical interest.

Metaphysical traditions associate black garnet with protection and grounding, a traditional belief rather than science.