How to tell if rhodonite is real
Real rhodonite is rose-pink, often black-veined, hardness 5.5 to 6.5, and a polished piece reads near 1.73 on a refractometer. Pyroxmangite needs a laboratory.
To tell if rhodonite is real, check colour and veining, hardness on a hidden spot, the broken edge, then a refractometer. Real rhodonite is rose-pink, often black-veined, hardness 5.5 to 6.5, with two cleavages at 92.5 degrees, and a polished piece reads near 1.73. Pyroxmangite matches all of these; only a laboratory separates it.
In short
- Start with the look, and it is distinctive. The Handbook of Mineralogy sheet gives rose-pink to brownish red, gray or yellow, with an exterior commonly black from manganese oxides and a white streak. The International Gem Society describes black dendritic, tree-like veins of manganese oxide in the massive material used for beads and carvings.
- The 1.73 spot rule: a polished piece of massive rhodonite gives a shadow edge near 1.73 on a refractometer (IGS). Rose quartz reads 1.544 and 1.553, bustamite reads lower, 1.640 to 1.710 on its sheet, and the gem society says bustamite's distinctly lower indices should distinguish it. Rhodochrosite's two indices, 1.597 and 1.810, sit either side.
- Hardness and the broken edge are free. Rhodonite is 5.5 to 6.5 with two perfect cleavages at 92.5 degrees plus a good third. Rhodochrosite, 3.5 to 4, is the commonest confusion, and the hardness rule for that pair is on the rhodochrosite-and-rhodonite page.
- A documented limit: pyroxmangite passes the home checks on this page. It is also a manganese silicate, with hardness 5.5 to 6, density 3.61 to 3.80, two perfect cleavages at 92 degrees and indices 1.728 to 1.758, overlapping rhodonite's. The gem society separates the two by birefringence, which is gemmological work.
- Fake rhodonite is less common than mislabelled rhodonite. The IGS says rhodonites typically receive no treatments and dyeing is rare. Beads sold as synthetic rhodonite exist, but the gem society could not establish whether they are laboratory-made rhodonite or an imitation.
| Mineral | Refractive index (sheet) | Hardness | Cleavage (sheet) | 20.00 g in water, calculated | Separated from rhodonite by |
|---|---|---|---|---|---|
| Rhodonite | 1.711–1.748; IGS massive shadow edge 1.73 | 5.5–6.5 | Perfect on {110} and {1-10} at 92.5 degrees; good on {001} | 14.40–14.68 g | - |
| Pyroxmangite | 1.728–1.758 | 5.5–6 | Perfect on two planes at 92 degrees; poor on two more | 14.46–14.74 g | Nothing at home; birefringence, per IGS |
| Bustamite | 1.640–1.710 | 5.5–6.5 | Perfect on {100}, good on two more | 13.98–14.17 g | Refractometer (IGS: distinctly lower indices); its sheet adds pink fades on exposure to light |
| Rhodochrosite | 1.597 and 1.810 | 3.5–4 | Perfect rhombohedral | 14.59 g | Hardness: a steel point marks it |
| Rose quartz | 1.544 and 1.553 | 7 | Rarely observable | 12.45 g | Refractometer or scale |
| Spessartine (manganese garnet) | 1.800, singly refractive | 7–7.5 | None recorded | 15.23 g | Scale, refractometer, broken edge |
How to tell if rhodonite is real: five checks, in order
Begin with a 10x lens and a lamp, and end, only if you need to, at a gem laboratory. Each check costs more than the last and removes one look-alike. The Handbook of Mineralogy sheet for rhodonite gives the numbers used throughout: hardness 5.5–6.5, measured density 3.57–3.76, cleavage perfect on {110} and {1-10} at 92.5 degrees and good on {001}, read from the rendered sheet.
- Day one, the look. Rose-pink to brownish red, a black manganese-oxide skin or black dendritic veins (IGS), and a white streak on the back of a tile where it will not show. White banding is a warning: the gem society notes that some beads sold as rhodonite carry white bands more characteristic of rhodochrosite.
- Hardness, on a hidden spot. A steel point that bites easily means a carbonate such as rhodochrosite. The method is on how to test mineral hardness properly, and the rhodochrosite pair has its own rule on is rhodochrosite the same as rhodonite, not repeated here.
- The broken edge. Two flat cleavages meeting close to a right angle, plus a third, fit rhodonite, and also pyroxmangite and bustamite among the pink candidates on this page. Rough, curved fracture everywhere points away from all three.
- Refractometer, on a polished face. A shadow edge near 1.73 fits rhodonite and pyroxmangite. A reading near 1.54 to 1.55 is quartz; one clearly lower than rhodonite's range suggests bustamite.
- Laboratory, for pyroxmangite. Nothing earlier on the list separates it.
The finish state is one of four labels: rhodonite or pyroxmangite; another pink mineral, named; rhodonite confirmed by a laboratory; or untested. For massive beads and carvings, step 1 to step 3 is usually the whole job, in our judgement. Dyed material in general is on how to tell if a crystal is dyed. The identification pages are indexed at the collecting guides.
What does rhodonite look like? The 1.73 spot rule
The 1.73 spot rule: on a polished piece of massive rhodonite, a gemmological refractometer shows a shadow edge near 1.73. The International Gem Society rhodonite article gives that figure for massive varieties, and its general range of 1.711 to 1.752 matches the Handbook sheet's 1.711 to 1.748 closely. Rhodonite is biaxial positive, and the IGS gives birefringence 0.011 to 0.014.
What the rule separates. Rose quartz, pink from inclusions on the quartz sheet, reads 1.544 and 1.553. The Handbook of Mineralogy sheet for bustamite prints indices from 1.640 to 1.710, and the gem society writes that bustamite gems are sometimes labelled rhodonite, with a similar but paler colour, and that bustamite's distinctly lower indices should distinguish it. Rhodochrosite's sheet prints 1.810 and 1.597, neither of them near 1.73.
What it does not separate. The Handbook of Mineralogy sheet for pyroxmangite prints 1.728 to 1.758, overlapping rhodonite's range. The rule says rhodonite or pyroxmangite, not rhodonite alone. A garnet, spessartine at 1.800, is a separate question, worked through on is rhodonite a garnet.
Is it rhodonite or pyroxmangite? Where home tests stop
Pyroxmangite passes every check on this page short of a laboratory, so a home test can say rhodonite or pyroxmangite and no more. Set side by side from the two sheets: hardness 5.5–6.5 against 5.5–6; density 3.57–3.76 against 3.61–3.80, which on a 20.00 g piece is 14.40 to 14.68 g in water against 14.46 to 14.74 g; two perfect cleavages at 92.5 degrees against 92 degrees; pink, with a black or brown oxidised exterior, on both. Treat this as a documented negative: on these numbers the overlap is complete.
The gem society names the separating property. It says cut pyroxmangite gems resemble rhodonites but their birefringence values differ. That needs a refractometer reading of both edges on a transparent cut stone, and in practice a gemmologist; massive material is a laboratory question, in our judgement.
Labels do not settle it either. The rhodonite, pyroxmangite, bustamite and spessartine sheets all name Broken Hill, New South Wales, in their Distribution fields, and the IGS notes that rhodonite can occur there with pyroxmangite and bustamite. A Broken Hill label narrows nothing among these four; the locality is on Broken Hill.
Is there fake rhodonite? What the gem society says
Treated or fake rhodonite is less documented than mislabelled rhodonite. The International Gem Society writes that rhodonites typically receive no treatments and that dyeing is rare. It says scientists have synthesised rhodonite for research, including thermoluminescence work, and that so-called synthetic rhodonites appear in jewellery, mostly as opaque pink to rose red beads with black veins.
Whether those beads are rhodonite at all is open. The gem society could not establish whether they contain laboratory-made rhodonite or another material imitating it, and suggests synthetic may be used there in the popular sense of simply not real. This page claims no more than that. For a bead, steps 1 to 3 above are the practical test; general imitations are on how to tell if a crystal is fake.
One property to know before testing: the IGS notes that perfect cleavage makes transparent rhodonite delicate, so do not scratch-test a faceted stone. The bustamite sheet adds that bustamite's Pink color fades on exposure to light; light sensitivity in general is on which minerals fade in light. Nothing on this site is offered for sale; the wanted list is the only commercial route.