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Former featured article Ammolite is a former featured article. Please see the links under Article milestones below for its original nomination page (for older articles, check the nomination archive) and why it was removed.
Main Page trophy This article appeared on Wikipedia's Main Page as Today's featured article on March 5, 2005.
Article milestones
Date Process Result
February 23, 2005 Featured article candidate Promoted
September 1, 2008 Featured article review Demoted
Current status: Former featured article

older comments[edit]

The one thing I'd like to see to improve the page would be a picture of some actual ammolite jewelry. Other than that, well done! Good to see another unique FA. Radagast 13:22, Feb 25, 2005 (UTC)

Korite has graciously fulfilled my request for images: the article now includes two images of the company's mining operations and an excellent image of fine ammolite jewellery. Of course, I'm glad you enjoyed the article prior to its embellishment. :) -- Hadal 05:37, 4 Mar 2005 (UTC)

What was that on the page?! There was a very inappropriate image. Sorry if I broke the page in the editing, but showing that on something linked to the front page is obviously not a good idea. Look in the page's history to see it, and be forewarned. Replaced with text "Eek!" etc. Sorry for sloppy editing.

The vandalism you saw was actually removed quite some time ago, long before you edited the correct image out; as you're not logged in, you were apparently served an outdated cached copy of the article. I've purged the cache, so you shouldn't see any more inappropriate images. -- Hadal 04:19, 5 Mar 2005 (UTC)


What does this mean? (excluding those used primarily as ornamental materials rather than discrete stones)??? I tried to articulate what I think is wrong with it, but it's falling into the "that's not right; it's not even wrong" category of gobbledygook. Could someone who understands the article's subject matter find a way to state whatever these words mean, in a way that a layman can grok? Blair P. Houghton 16:56, 5 Mar 2005 (UTC)

Um.. I can't think of a better way to phrase it succinctly. Ivory can be made into a discrete (distinct) stone (what is traditionally thought of as a gemstone, like the ammolite cabochons used in the jewellery depicted in this article), but it's primarily used to make things like sculptures and scrimshaw. Likewise, mother-of-pearl and tortoiseshell could be carved into discrete (separate, little, round) stones, but they're usually made into things like hair combs and boxes. Jet is usually carved into bracelets and linked necklaces. That's the distinction between an ornamental material and a gemstone, although the line can be a little blurry sometimes. I can't help much beyond explaining as I just have, but I hope it isn't quite "gobbledygook" to you now. -- Hadal 18:51, 5 Mar 2005 (UTC)
"Jet is usually carved into bracelets and linked necklaces"... This is true, but it has been used (and most likely still is in small amounts) as a gemstone. As there is no "current" or "common" adjective used in the sentence "It is one of the three biogenic gemstones, the other two being amber and pearl.", wouldn't jet qualify as fitting into this category? It's biogenic, and it exists as a gem albeit in small amounts. I would include it in this category. -- Yoimjamie 00:02, 23 Aug 2006 (UTC)

Regarding the three organic gemstones, maybe I'm thick, but isn't diamond organic? It is, after all, a carbon structure... am I missing something? Sorry if this is barking up the wrong tree.

You are right. Although ammolite is organic in the sense that it contains carbonates and carbonates contain carbon, I believe what the others truly mean is biogenic (made by life). -- — Ŭalabio 23:58, 2005 Mar 5 (UTC)
  • Okay. I think I fixed it up so it says what I think you guys say it says without the statement coming across as a croquet ball on a dinner table. BTW, there's no actual page for tortoiseshell as a precious material; not even a mention on tortoiseshell, the disambiguation page. Blair P. Houghton 00:27, 6 Mar 2005 (UTC)
No, diamond is not organic—unless you synthesize diamond out of peanut butter or your dog (cf. LifeGem). And even then you'd have to qualify it as a synthetic. There are inorganic sources of carbon; diamonds are formed at such great depths that it's unlikely the carbon came from animals or plants. That said, biogenic is perhaps a more precise term, even if organic is a perfectly acceptable qualifier as well. The footnote is a bit of a "croquet ball", but if it helps to dispell confusion, I'll let it be. As for tortoiseshell: I'll get around to writing a decent article on it soon. -- Hadal 02:47, 6 Mar 2005 (UTC)
Organic means carbon-based. All known life is organic, but not all organics are from life. The diamonds from the ground are probably abiogenic, while the diamonds from LifeGem are biogenic. All diamonds are organic. Ammolite, along with amber, et al, is best described as biogenic. -- — Ŭalabio 02:26, 2005 Mar 7 (UTC)
Nobody has removed your change to biogenic, despite the fact that a major definition of organic is, in fact, "of or relating to or derived from living organisms". (Not to mention that this definition was pretty clearly meant, when one considers context.) So I'm not sure what you're driving at; your change won't be reverted. As for your claim of diamond being organic simply because it contains carbon, you should be careful with whom you tell that to: check Wikipedia's own articles on organic compound and inorganic compound. You'll notice there are quite a few exceptions to the "carbon = organic" rule, and one exception is (usually) elemental carbon—i.e., diamond or graphite. It seems calling diamond "organic" isn't quite NPOV in chemistry circles. :) -- Hadal 02:50, 7 Mar 2005 (UTC)

There is yet another biogenic gemstone that you missed: coral. It has no article on Wikipedia — the Coral article is about coral reefs, and contains one (inaccurate) mention of coral as a gem. However, it is listed under Gemstone, and Googling for (coral gemstone -reef) brings up a plethora of jeweller's pages. And BTW, it is used primarily as a distinct stone :-) Freederick 02:04, 4 February 2007 (UTC)

I'll wait a few days for responses (this being a featured page and all that), and then edit the page to say: “ of the four biogenic gemstones, the other three being amber, coral, and pearl...” Freederick 02:04, 4 February 2007 (UTC)

If you are really going to make a point about biogenic gemstones you need to forget about trying to number them, because there are numerous other biogenic materials used as gemstones (taking a broad definition of gem). Off the top of my head, I can think of at least five others - ivory, bone, teeth, mother-of pearl, ebony (and other wood types). Of course this assumes the broadest view of what a gem is. SauliH 04:24, 4 February 2007 (UTC)

From Article:

These gemstones are differentiated from other precious, organically produced, ornamental materials such as ivory, jet, mother of pearl, tortoiseshell, etc., primarily by the ways in which they are used. Pearls, amber, and ammolite are considered to be jewels, while the others are treated more as textural objects.

This note seems to me some original research. Where is the source for this differentiation? Ammolite is a fossilized biogenic material. If one were to maintain that it belongs as a biogenic material along with amber, pearls, and coral, we need to be careful - after all much opal is from a fossilization process of seashells - which on the rationale of the article would make a major proportion of that gem - biogenic, petrified wood would also be biogenic - along with others also. This whole point in my opinion should be either cut from the article, or refined to state something factual. SauliH 04:40, 4 February 2007 (UTC)

BTW - can the author of this note please state what is meant by textural object? Also, WHO is considering pearls amber and ammolite to be jewels over the other materials? Please state your source!SauliH 04:45, 4 February 2007 (UTC)

Some Questions[edit]

Hello, currently I'm translating this article into German (de:Ammolit). However, I have some questions. --Elwe 09:33, 11 July 2005 (UTC)

  1. Does ammolite is really found only in the Bearpaw formation in Alberta and surrounding countries? What about the iridescent Ammonite from madagascar?
    Iridescent Ammonite from madagascar
    What about the lumachella from Italy? Of course, it has a brigther substrate, so the iridescence isn't visible as well.
  2. What has happened with the proteins in the nacre of the shells? Is it still there? If not, what material has replaced it? There must be a difference in the refractive index, so that the boundaries can reflect the light. Why is the aragonite not modified into clacite?
  3. What is the meaning of small, crawling stone? Is there a differnce between iniskim ans aapoak?
  4. What does negative in refractive index of Canadian material ..... 1.676-1.679; biaxial negative mean?
  5. Are the blue ammolites really more seldom beacus of the greater fragility of the finer layers responsible for the blues or because the ammonites hadn't produced small enough aragonit platelets?
  6. Why can prolonged exposure to sunlight also lead to bleaching? They are fully mineralized and containing no water.
  7. Through diagenesis, the shells were impregnated by trace elements present in these sediments, the most common of these being iron and magnesium, the former of which accounts for the predominance of the green colors. Really? The colours stem from inteference of reflected light, what is the iron for?
  8. What does crush material mean? majority or waste?

Thanks! --Elwe 09:33, 11 July 2005 (UTC)

Let's see if I can answer your questions satisfactorily:
  1. That's a good point; the article should read "Significant deposits of gem-quality ammolite is only found in...". I'll fix this oversight. The status of lumachella is already mentioned in the == Imitations == section.
  2. I presume the proteins have been mineralized. What exactly they've turned into, however, my references don't say. I'm not sure what you mean by "there must be a difference". In life, the nacreous proteins are there to hold the aragonite layers together; AFAIK they don't normally contribute significantly to light absorption, or at least don't affect the overlying iridescence of the shell. The aragonite is not modified into calcite due to the unusual geophysical environment of the ammolite deposits; as the references and the article state, this is owing to the protective bentonite sediments and resultant diagenesis.
  3. From what I've read, "small, crawling stone" refers to the iridescence, which (presumably in the eyes of the Blackfoot) made the stone appear to move. Iniskim and aapoak are different words with different meanings, both from the same language, each used by a different Blackfoot Confederacy tribe to refer to the same stone. The former is used by the Blackfeet and the latter by the Kainah, as defined in the article.
  4. In this context, negative refers to the optic sign; see Crystal optics#Anisotropic media.
  5. That's what the references say, but you bring up an interesting point. In any event, the article doesn't mean to imply that there is less ammolite with blue iridescence; rather, that gem-quality blue ammolite is more uncommon due to its inherent fragility. Does that make sense?
  6. I'm not entirely sure why, but again, that's what the references say. Perhaps the upper layers are rehydrated in some fashion following exposure, and the later evaporation causes damage to the microstructure? *shrug* I do know that unprocessed ammolite that's been soaked in water and left to dry in the sun will begin to flake.
  7. This sentence could also use clarification; the "green color" in this case could be the base colour of the nacre itself, or the iron could be affecting the layers of nacre. The reference I got this from (IGS) does not elaborate, so I cannot clarify until I've located more data.
  8. Most of it is waste, but a large portion is still good enough for commercial (low-end) jewellery. The word "crush" refers to the compaction of the material, which gives rise to tessellated cracks, etc. This article's lead image is crush material, for example.
Did the above help you? -- Hadal 08:11, 13 July 2005 (UTC)


This is a featured article. Why are we copying and pasting garbage from onto here? Tuxide 22:37, 23 August 2006 (UTC)

may be the page should be proposed for protection.--BMF81 00:28, 24 August 2006 (UTC)

I reverted the article to the last version that I believed was good and removed the copyvio tag, per discussion on IRC. The full article isn't a copyright violation, only part of it was. Tuxide 00:41, 24 August 2006 (UTC)

Propose addition of infobox[edit]

An iridescent ammonite from Madagascar.
Category fossilized, mineralized Ammonite shell
(repeating unit)
variable, often aragonite, calcite, pyrite, silica and others[1]
Color Gray to brown, sometimes with iridescent colors. [1]
Fracture uneven to granular[1]
Mohs scale hardness variable[1]
Luster greasy to dull[1]
Specific gravity usually about 2.70 (varies with mineral content)[1]
Polish luster vitreous[1]
Optical properties anomalous aggregate reaction [1]
Refractive index usually 1.52 - 1.68 (varies with mineral content)[1]
Birefringence usually 1.55 (varies with mineral content)[1]
Pleochroism none[1]
Ultraviolet fluorescence variable[1]

Being a featured article I was less apt to barge in like I normally do... I have been adding some infoboxes as a part of trying to provide some consistent lokk to gemology pages. If there are no objections I would add an infobox to the page giving an overview of mineralogical and gemological details. Much like Spessartite, and Grossular. SauliH 07:30, 28 January 2007 (UTC)

This is what I would add -

Source for data is GIA handbook. SauliH 07:40, 28 January 2007 (UTC)

"official gemstone of the Province of Alberta."[edit]

Does someone have a reference for "official gemstone of the Province of Alberta"? Neither the Legislature page nor the Executive Council booklet mention this. Thanks. --Qyd 01:03, 11 February 2007 (UTC)

Thanks for the ref. --Qyd 20:43, 20 July 2007 (UTC)

Ammolite as one of "three" biogenic gemstones[edit]

Coral earrings
Mourning jewellery: Jet Brooch, 19th century.

It is one of the three biogenic gemstones, the other two being amber and pearl.

Why three? There are other biogenic substances used as gemstones, like jet and coral. If anyone is going to argue that they "aren't stones" or "aren't minerals," then neither pearl nor amber belong on that list. I think "three" should be changed to "several," and I am doing so. --♦♦♦Vlmastra♦♦♦ 15:47, 27 October 2007 (UTC)

Edit: I just spotted the note, but coral is used quite commonly as a gemstone, and jet was previously common as a gemstone much in the same manner as amber. Therefore, I still support my change. --♦♦♦Vlmastra♦♦♦ 15:50, 27 October 2007 (UTC)

huh? source of color[edit]

Huh? 1) In "Properties" the color comes from interference (thickness of plates); in "Formation ...", the green color comes from iron. 2) In Wikipedia "aragonite", this polymorph is stable 10^7 to 10^8 years at standard temperature and pressure. How do bentonite layers prevent alteration to calcite? Jahigginbotham (talk) 03:07, 18 April 2008 (UTC)jahigginbotham 18apr2008

Mineral/chemical composition[edit]

What is the chemical/mineralogic composition of this? Is is like opal... and a mineraloid gel, or is it actually a mineral? The article is unclear... (talk) 21:24, 13 May 2009 (UTC)

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  1. ^ a b c d e f g h i j k l (Gia), Gemological. Gem Reference Guide. City: Gemological Institute of America (GIA), 1988. ISBN 0-87311-019-6