silicates
Almandine
Fe2+3Al2(SiO4)3
- Also known as
- carbuncleprecious garnet
- Crystal system
- cubic
- Hardness
- 7–7.5 on the Mohs scale
- Lustre
- vitreous
- Colour
- Deep red to reddish brown, often almost black
- Where it forms
- In medium-grade metamorphic rocks — schists and gneisses — where it is one of the defining minerals used to grade metamorphism.
- Chiefly from
- IndiaSri LankaBrazilAlaska, United States
Why it is that colour
Iron. Almandine is the iron end member of the aluminium garnets, and it is the commonest garnet by a wide margin.
Safety
Safe to handle.
Where it comes from
The workhorse of the industrial abrasive trade, mined at scale in India and Australia. Gem-quality material is common and inexpensive.
Historical use
The garnet of Victorian jewellery, Anglo-Saxon cloisonné, and Bohemian garnet work. Almandine is what most people picture when they hear the word.
Recorded as history and attributed where possible. That a stone was used for something establishes that people used it, not that it worked.
What is attributed to it, and since when
Most historical references to garnet are to this. Named after Alabanda in Asia Minor, a cutting centre in antiquity.
Described, not endorsed. Dating a claim is not the same as assessing it — but an association that first appears in a book published in 1985 is not an ancient inheritance, whatever the label says. A sincere account of feeling better is compatible with the stone doing nothing — see the placebo effect.
Worth knowing
Almandine's real importance is as an index mineral. Metamorphic geologists grade rocks by which minerals appear as temperature and pressure rise, and the garnet zone is one of the standard markers — its first appearance in a sequence of schists tells you the rock crossed a particular threshold. Whole mountain belts are mapped this way.
Identity checked against IMA-CNMNC master list, June 2025.