Is there any authoritative reference to the claim that glass decomposes in one million years? I came across that figure multiple times (for example, 1, 2, 3). They often cite The New Hampshire Department of Environmental Services which, in turn, cites "U.S. National Park Service; Mote Marine Lab, Sarasota, FL." (some websites cite the latter directly), but I couldn't find this elusive primary source (I scoured several Google search pages). The last link (the word "websites") includes this reference: "Sources: U.S. National Park Service; Mote Marine Lab, Sarasota, FL and “Garbage In, Garbage Out.” Audobon magazine, Sept/Oct 1998." But an article that has such a title doesn't contain any information about million-year decomposition – and maybe it's not the article in question because it's dated differently. Is Skeptics SE going to help me out?

  • 2
    Extended discussion on what it means to degrade glass, including pseudo-answers to moved to chat. Please do not continue that here.
    – Oddthinking
    Commented Dec 28, 2021 at 22:50
  • It would be worth looking to see if physicists have simulated glass for that long, that would be an answer if you believe the models they used in their simulation amazon.com/Atomistic-Computer-Simulations-Inorganic-glasses/dp/… Commented Dec 30, 2021 at 15:53
  • @CharlieCrown all I see is an offer to buy some book Commented Dec 30, 2021 at 16:23
  • It is just an example of the fields existence. If it was an answer, it wouldn't be a comment Commented Dec 30, 2021 at 16:28
  • Could this be about different definitions of 'decompose' -i.e. the "a bottle left on the forest floor might not break down into sand‐sized particles for a million years" is not real decomposition, which is OK, because it is a mineral already, so the classic way for stuff to 'decompose', i.e. turn into minerals and gas is not open to glass.
    – bukwyrm
    Commented Jan 19, 2022 at 14:36

2 Answers 2



According to Metallurgical Slags: Environmental Geochemistry and Resource Potential

The oldest preserved glass formed 300 million years ago

The statement is in chapter 4 "Weathering of Slags" by Jakub Kierczak, Anna Pietranik and Nadine M. Piatak

See also Immobilisation of Radioactive Wastes in Glass which is chapter 17 of An Introduction to Nuclear Waste Immobilisation, 2005 (alterative link):

Some of these glasses have been in the natural environment for about 300 million years with low alteration rates of only tenths of a millimetre per million years.

However, as far as some supposedly authoritative reference claiming one million years, Environmental and Workplace Safety: A Guide for University, Hospital, and School Managers (1996) at page 256 say:

A glass bottle takes one million years to decompose

The 21 September 1972 New York Times article NATURE RECYCLES CANS, BUT SLOWLY says:

Perhaps the least perishable of the commonly thrown‐away materials is glass. Prof. Evelyn C. Marboe, a glass chemist, said a bottle left on the forest floor might not break down into sand‐sized particles for a million years.

“Glass is one of the most durable materials known,” Professor Marboe said. “We have glass beads from Egypt that are 4,000 years old and, of course, there are many examples of glasslike rock—such as obsidian—that may be as old as the earth.”

So people saying "one million years" for glass bottles goes back at least to 1972, but really glass can last much longer.

  • What page? 4 more to go... Commented Dec 30, 2021 at 1:02
  • @SergeyZolotarev hmm, all I can say right now is it's on the last page of section 4.6
    – DavePhD
    Commented Dec 30, 2021 at 1:54
  • @SergeyZolotarev This is a more official source of the chapter with the statement. pubs.rsc.org/en/content/chapter/bk9781788018876-00125/…
    – DavePhD
    Commented Dec 30, 2021 at 1:56
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    That 300 million glass is rhyolitic, and rhyolite, Lexico says, is "volcanic rock of granitic composition". It's probably not a good approximation of regular bottle glass. I found a non-paywalled way to access that passage: google.ru/books/edition/Metallurgical_Slags/… Commented Dec 30, 2021 at 14:16
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    A glass bottle exposed to the elements and getting into storms regularly might not last that long.
    – gnasher729
    Commented Jan 5, 2022 at 20:52

The South China Morning Post reports that some glass beads from an asteroid collision lasted over 3 billion years - far longer than the suggested 1 million years:

[Glikson and Hickman] found tiny glass beads, called spherules, which are formed by vaporised material from an asteroid's impact [...] It dates from 3.46 billion years ago.

  • 1
    Could you please provide references for these claims as per our evidentiary requirements - as expert opinion is welcome only when supported by good quality references. Commented Jan 8, 2022 at 7:53
  • 1
    Please provide some references to support your claims.
    – Oddthinking
    Commented Jan 8, 2022 at 8:37
  • Made a severe edit to remove the unreferenced claims.
    – Oddthinking
    Commented Jan 9, 2022 at 6:52

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