How do I use Mindat and RRUFF to check an identification?

Use Mindat to ask "what has been found at this locality, and what does it look like there?" and RRUFF to ask "what does a confirmed sample of this species measure like?" Mindat is a community database of minerals and localities run as an outreach project of the Hudson Institute of Mineralogy [1]. RRUFF is a University of Arizona database of Raman spectra, X-ray diffraction patterns and chemistry measured on well-characterized samples [2][3]. Neither identifies your specimen for you: Mindat narrows the candidates, and RRUFF is the reference a lab compares your specimen's spectrum against. The IMA list of minerals settles whether a name is current. Below: how to read each, and how far to trust it.

Three sources, three jobs

Reading a Mindat locality page

A Mindat locality page sits in a hierarchy, from country down through state or province, county, district and mine, sometimes to a single pit or level. Each page carries a list of the minerals reported there, photos uploaded by collectors and dealers, and often references and notes.

Using the species list to narrow your candidates

1. Find the most specific locality you can. If your label says only a county, start there and look at the mines and pits beneath it. A district list is a long list; a single mine's list is short.
2. Read the whole list, not only the famous species. Your brassy cubes are more likely the common pyrite than a rare sulfide that appears once.
3. Open the photos for your candidates. A photo of the species from the same locality shows the habit, color and associations you should expect. If your specimen looks like the local pyrite photos and nothing like the local marcasite, that is real evidence.
4. Check the associations. Minerals come in families. If your candidate is usually found with species that are not on the list, be cautious.
5. Write down what you checked. Note the locality page and the date in your catalog. Mindat pages change as contributors add and correct entries.

How reliable the lists are

Treat a Mindat species list the way you would treat a well-kept but crowd-sourced notebook. Many entries are backed by published references or by specimens analyzed and documented by their owners, but an entry can also rest on a single report or an old label. Look for a reference, an analysis note or a photo for the species you care about. A species that appears on the list with no photo, no reference and no notes is a weaker lead than one with all three. When a locality page and your tests disagree, trust the tests and keep looking.

Mindat also runs discussion forums. Its 2009 advice to people sorting collections suggests posting "photos about things you need help identifying" [1]. Forum replies are other collectors' opinions; use them to decide what to test next.

Locality pages and your labels

Mindat's locality hierarchy is also a good model for writing the locality on a label, from country down to mine. How precise a locality should be, and when to withhold coordinates, is covered on how precise a locality should be.

Reading a RRUFF species page

RRUFF describes itself, through its catalog entry at the Science Education Resource Center, as "an integrated database of Raman spectra, X-ray diffraction and chemistry data for minerals," searchable by mineral name or composition [2]. Each sample record carries photos, Raman spectra, powder diffraction patterns, measured chemistry, and locality and source information [2].

What makes RRUFF data trustworthy is how the samples were checked. A 2005 Geological Society of America abstract by the project team describes the sequence: each sample is screened for Raman quality, then confirmed by X-ray powder diffraction, studied by single-crystal diffraction, and analyzed for chemistry by electron microprobe [3]. The same abstract describes "an automated search match engine" for comparing spectral data against the database, with sample details, localities, photographs and data free to access [3].

What a collector does with it

• Compare a lab result. If a lab gives you a Raman spectrum, look up the matched species in RRUFF and compare the peaks yourself.
• See the range within a species. Several samples of one species from different localities show how much spectra and chemistry vary.
• Learn what a species really is. The chemistry field shows the composition a confirmed sample actually had, which can differ from an idealized formula.

You cannot run a Raman or XRD test at home, so RRUFF is a reference for checking, not a home test. In October 2026, species links of the form rruff.info/{mineral} redirected to a page on rruff.net; if an old link fails, search the current site by mineral name.

What a database match can and cannot prove

A 2009 study in Spectroscopy by Thermo Fisher Scientific and University of Arizona authors used RRUFF spectra from "over 2,000 mineral species" (as of that year) as the reference library for screening semiprecious stones [5]. The authors treated a match value above 90 as "a strong indicator" that two minerals are the same, and they sorted stones into correctly labeled, incorrectly labeled and inconclusive, arguing that "I don't know" is preferable to a misclassification [5]. They also found the limits: synthetic corundum matched natural corundum, emerald and aquamarine (both beryl) gave similar spectra, and an inclusion of rutile in corundum dropped the match to 65 [5]. A database match tells you the species. It does not tell you whether a stone is natural, treated or synthetic, or which variety it is.

Checking the name against the IMA list

The IMA list is the official list of valid mineral species. The July 2026 edition calls itself "a work in progress," covers 6,226 currently valid species, and is updated regularly [4]. Each entry gives the accepted name, the approved formula and a status code [4]:

If a name on your label is not on the list, it may be a variety name (amethyst is a variety of quartz), a trade name, an old name for a species that was renamed, or a discredited name. The difference between species, variety and trade name, and how to write the current name on a label, is on species, variety and trade names. The species count lives there too, with its date.

When the databases are not enough

If Mindat narrows your specimen to two or three candidates and hand tests cannot separate them, the next step is an instrument. Getting a specimen tested explains XRD, Raman and chemical analysis in plain terms, with prices from named labs and how to send a sample.

References

1. Mindat.org, Bri Dragonne, "Advice for people selling and sorting a mineral collection," article 836, last updated November 19, 2009 (site footer read October 2026). https://www.mindat.org/article.php/836/Advice+for+people+selling+and+sorting+a+mineral+collection.
2. Science Education Resource Center (SERC), Carleton College, catalog entry "RRUFF Project" (The University of Arizona), read October 2026. https://serc.carleton.edu/resources/21028.html
3. P.R. Mooney, R.F. Dembowski, T.A. Laetsch, J. Zwick, R.T. Downs and R. Lu, "RRUFF Project: Developing an Integrated Database of Raman and Infrared Spectra," Geological Society of America Annual Meeting, Salt Lake City, abstract, October 17, 2005. https://gsa.confex.com/gsa/2005AM/webprogram/Paper92745.html
4. International Mineralogical Association, Commission on New Minerals, Nomenclature and Classification, "The New IMA List of Minerals: A Work in Progress," updated July 2026. https://cnmnc.units.it/files/editor/IMA_Master_List_%282026-07%29.pdf
5. S. Lowry, D. Wieboldt, D. Dalrymple, R. Jasinevicius and R.T. Downs, "The Use of a Raman Spectral Database of Minerals for Rapid Verification of Semiprecious Gemstones," Spectroscopy 24(5), May 1, 2009. https://www.spectroscopyonline.com/view/use-raman-spectral-database-minerals-rapid-verification-semiprecious-gemstones