Melanite Garnet Identification Guide
How to identify melanite, the opaque black titanium-bearing andradite garnet, by its luster, hardness, density, and crystal form.
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What Melanite Garnet Looks Like
Melanite is the black, titanium-bearing variety of andradite garnet (a calcium-iron garnet). It is opaque jet-black with a bright vitreous-to-resinous, almost submetallic luster. It commonly forms well-shaped isometric crystals (dodecahedra and trapezohedra) with sharp faces, prized by collectors.
- Color: opaque black (sometimes very dark brown)
- Luster: vitreous to resinous, can look subadamantine/submetallic
- Transparency: opaque
- Crystal habit: isometric dodecahedra and trapezohedra, often sharp and lustrous
Step-by-Step Field ID Checklist
- Confirm garnet crystal form - equant isometric crystals with 12 or 24 faces and no cleavage.
- Note the black color with bright luster - melanite looks glassy-to-shiny black, not dull.
- Test hardness - it scratches glass (Mohs 6.5-7).
- Check the streak - white to pale gray/brown (unlike metallic black minerals, which give dark streaks).
- Heft it - dense for its size.
Key Diagnostic Tests
- Mohs hardness: about 6.5-7.
- Streak: white to grayish - critical for separating it from metallic black minerals.
- Cleavage/fracture: no cleavage; conchoidal to uneven fracture.
- Specific gravity: roughly 3.7-3.9 (andradite range), heavy.
- Magnetism: iron-bearing andradite can show a weak magnetic response.
- Non-metallic: the white streak and vitreous luster confirm it is a silicate garnet, not an ore mineral.
Common Look-Alikes and How to Tell Them Apart
- Schorl (black tourmaline): forms elongated striated prisms (trigonal), not equant garnet crystals; melanite is blocky and isometric.
- Magnetite: strongly magnetic, has a black streak, and lower hardness; melanite has a white streak and only weak magnetism.
- Black spinel: also isometric but typically forms octahedra; melanite forms dodecahedra/trapezohedra and is andradite-composition.
- Obsidian (black): glass with conchoidal fracture and no crystal faces; melanite shows sharp crystal forms.
- Black andradite vs schorl quick test: crystal shape (blocky garnet vs striated prism) is the fastest separator.
Where It Is Typically Found
Melanite occurs in alkaline igneous rocks (nepheline syenites, phonolites), skarns, and contact-metamorphic zones. Notable localities include Italy (Vesuvius/Frascati area), Germany (Kaiserstuhl), France, Russia, and parts of the USA.
Frequently asked questions
How can you tell if it's real melanite garnet?
Look for opaque black isometric garnet crystals (dodecahedra/trapezohedra) with a bright vitreous-to-resinous luster, no cleavage, Mohs 6.5-7 (scratches glass), and a white streak, which separates it from metallic black minerals.
What is melanite garnet?
Melanite is the black, titanium-rich variety of andradite garnet, a calcium-iron garnet. Its color comes from titanium and iron, and it is valued for sharp, lustrous black crystals.
Melanite vs black tourmaline (schorl): how do you tell them apart?
Melanite forms blocky, equant isometric garnet crystals with no cleavage, while schorl forms elongated, striated three-sided prisms. The crystal shape is the quickest way to distinguish them.
Is melanite garnet magnetic?
It can show a weak magnetic response because it is iron-bearing andradite, but it is not strongly magnetic like magnetite. Combined with its white streak, this helps separate it from magnetite, which is strongly magnetic with a black streak.