Rainbow Hematite: Grading & Localities
Fe2O3 — iron’s prism‑coat in the wild. (And yes, if you typed “Hemtite,” your rock is forgiving. Your spell‑checker… slightly less so.) 🌈🪨
Creative aliases for listings: Aurora Iron, Prism‑Rose Hematite, Arcstone, Star‑Sheen Hematite, Peacock Iron.
🧭 How We Grade Rainbow Hematite
Rainbow hematite is hematite with natural iridescence. In hand, the best pieces show a wide color range, continuous coverage, and a silky metallic luster without rubs. We evaluate both optics (color, coverage, angle behavior) and structure (drusy quality, integrity, thickness, and matrix appeal), plus provenance. Some deposits (notably in Brazil) produce material with a distinctive, angle‑stable “patch” iridescence; others yield thinner films or coatings that favor blues/greens. Different geology, same goal: maximum “wow.”
- Hue range & saturation: violets → teals → golds. Broader range and strong saturation score higher.
- Coverage: continuous sheen across the display face beats spotty/edge‑only color.
- Angle behavior: some Brazilian pieces keep color patches steady as you tilt; others shift like a soap bubble. Both can be desirable—note it in your listing.
- Luster & contrast: crisp metallic or submetallic luster with fine micro‑facets makes colors pop.
- Condition: minimal rubs on druse, no flaking, intact edges, and stable matrix.
- Form & aesthetics: balanced outline, pleasing negative space, and interesting micro‑textures (iron roses, botryoids, or silky druse).
- Provenance: well‑documented localities (e.g., Andrade seam old‑stock) command premiums.
🎚️ Practical Grading Scale (Specimens)
| Grade (creative label) | Optical Qualities | Structure & Condition | Notes / Use |
|---|---|---|---|
| Aurora Prime (AAA) | Full spectrum; saturated, continuous color; excellent luster; angle‑stable or beautifully dynamic. | Pristine druse/roses; no rubs; strong matrix; gallery aesthetics. | Showpiece / museum; provenance and documentation expected. |
| Prism Crest (AA) | Wide color range; minor soft zones; high luster. | Tiny, non‑distracting edge wear; stable; good form. | Exhibition/collector; excellent value vs. AAA. |
| Halo Select (A) | Distinct but partial coverage; strong in one palette (e.g., teal/blue); good sparkle. | Minor rubs; cosmetic repairs acceptable if disclosed. | Cabinet specimen; ideal for teaching optics. |
| Arc Flash (B) | Patchy color or narrow palette; moderate luster. | Noticeable wear or uneven druse; still solid. | Decorative/entry‑level; good for larger formats. |
| Study Core (C) | Subtle/limited iridescence; mainly metallic body color. | Wear present; stable enough to handle. | Educational kits; cutting tests; texture reference. |
💍 Grading for Jewelry Use (Cabochons & Plates)
- Surface durability: choose tight, fine druse or compact “iron rose” textures; avoid friable crusts.
- Thickness & backing: stable backing (quartz, obsidian, or metal plate) protects the iridescent face; disclose composites.
- Color window: pick stones with saturated, front‑facing display under soft LED—what the wearer sees at arm’s length.
- Finish: avoid over‑polishing that thins or removes the rainbow; keep a light hand when lapping.
- Setting: bezel lips should not rub the iridescent face; consider shadow‑box bezels for drama + protection.
Quick laugh: rainbow hematite loves compliments and low‑friction friendships—both reduce abrasion. 😉
📜 Provenance & Market Notes
The Andrade mine (João Monlevade, Minas Gerais, Brazil) produced the most famous “rainbow hematite” of the 1990s, introduced widely to the U.S. by dealer Rock Currier. Old‑stock accounts describe a truckload‑scale import (≈15 tons), with later scarcity tied to the seam lying under a haul road, limiting further extraction. Well‑documented Andrade pieces typically command premium pricing in today’s market.
- Mechanism note: Andrade material shows angle‑stable color patches linked to a periodic nanorod substructure within hematite itself (not just a surface film). This gives a refined, “structural color” look prized by collectors.
- Elsewhere: Other localities can show iridescence from extremely fine surface layers rich in Al–P nano‑phases on hematite; both modes are natural and attractive—describe what you see.
🗺️ Localities at a Glance (collector‑oriented)
| Region / Mine | Typical Material | Palette & Behavior | Notes for Listings |
|---|---|---|---|
| Andrade Mine, João Monlevade, Minas Gerais, Brazil | Specular seams; drusy plates; iron‑rose fragments. | Bold patches of violet/teal/gold; often angle‑stable. | Classic “Aurora Iron”; old‑stock scarce—note provenance when known. |
| Pico Mine, Nova Lima, Minas Gerais, Brazil | Hematite with thin iridescent coloration along fractures. | Subtle linear rainbows; good teaching pieces. | List as “Pico Mine, Quadrilátero Ferrífero” when documented. |
| El Salvador Mine, Sierra Mojada, Coahuila, Mexico | Massive fine‑grained hematite with blue‑green iridescent coating. | Deep blues/greens; surface‑film style. | State “Sierra Mojada district” for clarity; color can be dramatic. |
| USA (Quartz Mountain, Oregon; Alaska) | Specimens showing periodic surface textures; smaller sizes. | Varied; may show stacked nano‑textures similar to Brazilian material. | Provenance labels elevate value; expect smaller but instructive pieces. |
| Italy (classic hematite localities) | Specularite/iron‑rose hematite; some iridescent examples studied historically. | Subtle rainbows; more often aesthetic hematite than “rainbow” showstoppers. | Use “Italy, classic iron districts” when documentation supports it. |
| Morocco (Taouz/Errachidia) — market cousin | Spectacular iridescent goethite, often sold as “rainbow hematite.” | Peacock sheens over botryoidal/spire forms. | Label accurately as goethite; it’s gorgeous and distinct from hematite. |
Locality availability fluctuates with mine access and surface exposures—expect Andrade old‑stock to surface intermittently via collections and estates.
🔎 Authenticity & Look‑alikes (label like a pro)
Quick ID checks
- Streak: hematite gives a red‑brown streak.
- Magnetism: weak to none; strong magnets suggest magnetite or synthetic ferrite (“magnetic hematite”).
- Luster & texture: drusy sparkle or iron‑rose plates are common host textures.
Common confusions
- Rainbow goethite (FeO(OH)): a legitimate, beautiful mineral that’s frequently sold as “rainbow hematite.” List it correctly—collectors appreciate accuracy.
- PVD‑coated beads: “titanium hematite” has a vapor‑deposited metal coating; attractive, but not natural iridescence.
Disclosure language
Use: “Natural iridescence on hematite (locality…), uncoated.” For goethite: “Natural iridescent goethite (often marketed as ‘rainbow hematite’).” For coated goods: “Hematite with PVD Ti‑coating.”
❓ FAQ
Is the rainbow a surface film or something inside the hematite?
Both exist in nature. Andrade (Brazil) is famous for a structural nano‑pattern within hematite that creates angle‑stable color patches. Other localities can show ultra‑thin, Al‑P‑rich nanolayers on hematite that act as interference films. Describe what your specimen shows and cite the source when possible.
Which locality is most valued?
Documented Andrade pieces lead the market due to beauty, history, and scarcity. Pico (Brazil) and Sierra Mojada (Mexico) examples are sought for teaching and aesthetics. Iridescent goethite from Morocco is a separate collectible with its own fan base—label accurately.
How should I phrase grades in a product listing?
Use a short descriptor plus your creative label, e.g., “Aurora Prime (AAA): full‑spectrum, angle‑stable, uncoated; Andrade, Brazil; old‑stock.”
✨ The Takeaway
Grade rainbow hematite by color breadth, coverage, luster, and integrity—then let provenance do its magic. Andrade old‑stock sets the benchmark; other localities add variety and teaching value. Label clearly (especially vs. goethite and coated goods), and your customers will see exactly why that tiny iron prism has such a big personality.
Final wink: It’s hematite wearing festival makeup—still grounded, just more likely to be photographed. 📸🌈