Data sources
Everywhere Material World draws its facts from — what each source is, what it is good for and where it falls short. Some of them we can quote directly; others we read to check ourselves against but cannot reproduce, and those say so.
Wikidata
Quoted on these pagesWikimedia Foundation
- Terms of reuse
- In the public domain
- Licence
- Creative Commons CC0 1.0 Universal (public domain dedication)
- Terms read
- On the publisher's own site, 2026-08-03
A collaboratively maintained database of structured facts, run by the Wikimedia Foundation. Material World uses it for identifiers, chemical formulae and basic properties, and always alongside a second source where the figure matters. Its structured data is in the public domain, so we are free to publish from it; we credit it anyway. Item descriptions and images carry separate terms and are assessed on their own.
Wikimedia Commons
Read, but not quotedWikimedia Foundation
- Terms of reuse
- Not established
- Licence
- Per-file — there is no site-wide licence
- Terms read
- Not yet on the publisher's own site
Wikimedia's media library. Listed so that any picture we use can be traced to where it came from rather than to a bare address. There is no single licence covering it — every file carries its own terms, from public domain through share-alike to material that should never have been uploaded — so each file has to be cleared individually.
USGS Mineral Commodity Summaries
Quoted on these pagesUnited States Geological Survey
- Terms of reuse
- In the public domain
- Licence
- US Government work — not subject to domestic copyright (17 U.S.C. §105)
- Terms read
- Not yet on the publisher's own site
The United States Geological Survey's annual review of mineral production, reserves and trade. An authoritative government source, used for production and occurrence figures. Works by US federal employees are not covered by domestic copyright, and the USGS asks for credit as a courtesy. We have not yet been able to read the agency's own terms page, so we treat that position as provisional.
Mindat.org
Read, but not quotedHudson Institute of Mineralogy
- Terms of reuse
- Not established
- Licence
- Not established
- Terms read
- Not yet on the publisher's own site
The largest mineral locality database, maintained by the Hudson Institute of Mineralogy. A valuable reference for occurrence and locality information. Its terms could not be read, so its position is unknown — which means nobody has established it, not that reuse is permitted. Until that is settled, nothing here rests on it.
IMA Commission on New Minerals, Nomenclature and Classification
Read, but not quotedInternational Mineralogical Association
- Terms of reuse
- Not established
- Licence
- No licence statement is published
- Terms read
- On the publisher's own site, 2026-08-03
The international body that decides which minerals are recognised species and what they are called — the naming authority for mineralogy. Its lists are published without any licence or copyright statement at all, so there is nothing to rely on. Nothing here is taken from those lists until the commission can tell us where they stand.
CRC Handbook of Chemistry and Physics
Read, but not quotedCRC Press / Taylor & Francis
- Terms of reuse
- Permission needed to reproduce
- Licence
- Commercially published reference work, all rights reserved
- Terms read
- Not yet on the publisher's own site
A standard printed reference for physical and chemical constants. We read it to check figures against rather than to take them from: it is a commercial work with rights reserved, so reproducing its tables needs permission. Where a figure here agrees with it, that agreement is noted, and the figure itself always comes from somewhere we are free to quote.
NIST — National Institute of Standards and Technology
Quoted on these pagesUnited States Department of Commerce
- Terms of reuse
- Open, with credit required
- Licence
- US Government work — public information, credit requested
- Terms read
- On the publisher's own site, 2026-08-03
The US National Institute of Standards and Technology, the reference point for measurement and physical constants. Information on its sites is public and may be copied, with credit requested. We treat that request as binding even though it is not legally compelled. One caveat NIST states itself: a mention of a commercial product is not an endorsement, and nothing sourced here is presented as a NIST recommendation.
PubChem
Read, but not quotedUS National Library of Medicine
- Terms of reuse
- Permission needed to reproduce
- Licence
- Mixed — aggregated third-party content, rights retained by depositors
- Terms read
- On the publisher's own site, 2026-08-03
The National Library of Medicine's chemical information service. It looks like a public-domain government dataset and is not: it aggregates hundreds of contributed datasets whose depositors keep their own rights. We read it to check figures against rather than to take them from, so nothing here rests on it alone.
Crystallography Open Database
Quoted on these pagesCOD Advisory Board / Vilnius University
- Terms of reuse
- In the public domain
- Licence
- CC0 — contributors place data in the public domain
- Terms read
- On the publisher's own site, 2026-08-03
An open collection of crystal structures maintained by an academic advisory board. Its contributors have placed their data in the public domain, so we are free to publish from it. Used for crystal system and structural data. The underlying measurements were never copyrightable in any case; what the dedication settles is the status of the collection itself.
RRUFF Project
Read, but not quotedUniversity of Arizona / RRUFF Project
- Terms of reuse
- Not established
- Licence
- Not established — no terms published
- Terms read
- On the publisher's own site, 2026-08-04
A University of Arizona project publishing spectra and reference data for minerals, including a copy of the international mineral list. The site publishes no terms of any kind — no licence, no copyright page — so there is nothing to assess and its position stays unknown. Settling it means writing to the project.
Smithsonian Open Access
Read, but not quotedSmithsonian Institution
- Terms of reuse
- Not established
- Licence
- Not established
- Terms read
- Not yet on the publisher's own site
The Smithsonian Institution's open access programme, covering its collections including mineral specimens. It is widely described as public domain and that is very likely right — but we record what we have actually read, and we have not been able to reach its terms page. Until we have, the status stays unknown.
And our own writing
The summaries, the explanations of why a material behaves as it does, and the reasoning on these pages are written here rather than taken from anywhere. They are named on each page so you can always tell the two apart. Writing of our own cannot corroborate itself, so where something rests on it alone, it carries a lower confidence for that reason.
Each entry describes what a publisher’s own site said, and when we read it. None of it is legal advice, and nothing here asserts that any particular use is lawful.