Talk:Silicon dioxide

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search

Silicon dioxide in food[edit]

Can you please tell me why I would find Silicon dioxide in the ingredients list on a packet of food and how safe is it to consume?

I second this --Plonk420 22:09, 19 Apr 2005 (UTC)

While I'm not sure why it exactly would be an *additive*, I do know that many people commonly ingest it - in the form of vegetables. Silica is fairly common in plant cell walls. One study I know of (there might be more) suggests that silicon dioxide may help lower cholesterol [1]. Of course, I doubt that that's what Burger King had in mind. One theory says that silica is added to increase the crunch in, say, pies or burgers. Silica is poorly absorbed by the body, so it shouldn't be too much of an issue (and again, it's commonly found in edible plants). Im guessing that the danger with eating those silica gel packets found in beef jerky packages and other snacks (used to keep the pack dry) is the possibility of *inhaling* it. That would cause silicosis, which would be bad. As a food additive, it *should* be stuck on food well enought that inhalation shouldn't be a problem. bluemonq 23:26, 7 May 2006 (UTC)

-It is used as a drying agent in powdered typed foods. — Preceding unsigned comment added by 2601:187:4000:DDBF:A4EE:126:6A5F:2DD5 (talk) 12:58, 7 June 2017 (UTC)

I was also looking it up to see why it is used in food, but found no answer. I noticed it's the last ingredient in Nestea iced tea mix, and that can't be for "crunchiness" since liqueds aren't normally crunchy. (talk) 23:18, 20 July 2008 (UTC)
silicon Dioxide is used in the making of bread, made and baked in Wal-Mart Stores in the Northeast US. The bread ingredients label

says "& Not more than 2% Silicon Dioxide added (as an anti-caking agent)" It also appears again in the same list saying "Not more than 2% each of Calcim Silicate & Silicon Dioxide added (as an anti-caking agent)" (talk) 18:06, 07 Dec 2008 (UTC)

Inhaling crystalline silica DUST can cause silicosis. The gel packets dont have dust, they typically have beads. If you want to see why you should not eat them, pour a fresh dry pack of the beads into water and watch them explode...

Speaking of all this, the Burger King page was a little bothersome, and the SiO2 was hard to find mentioned- would somebody perhaps just compile a list or something so that we wouldn't have to look so hard or pick on Burger King?--Honalululand 20:47, 16 January 2007 (UTC)

When Companies mess up and add too much Silicon dioxide people get pretty sick. My 1 year son went to the hospital over night when we was throwing up. I looked on the ingredients list and saw Silicon dioxide. I thought in my head,"why do they have silicon in food?". Vstmassie (talk) 17:09, 23 April 2008 (UTC)

Please do not take this the wrong way but maybe it was something else that made your little boy sick? Cross contamination of prep surfaces, not sufficiently sanitized containers or hands or something quite other and random (children get stomach upsets and do vomit on occasion.) It's highly unlikely that it was due to too much "silicon" in his food. As to why it is in Nestea mix it is as an anti-caking agent, it prevents "clumping" and hardening of the powder due to exposure to air (moisture.) That is it's primary purpose when added to foods and then it seems to mostly be used in powdered and dehydrated items.) —Preceding unsigned comment added by (talk) 19:17, 30 January 2009 (UTC)

There seems to be some evidence of potential adverse health effects from ingestion. Eg Not sure how to summarize that in the article Raisins31415 (talk) 15:55, 2 April 2021 (UTC)

Use in tires[edit]

Silica is now being used in motorcycle tire manufacturing. It makes the tires more compliant and temperature stable. This lets manufacturers make tires that grip better and still handle loads, without excessive wear from higher temperatures. It also affects wet weather traction. 2601:8:AA00:2DC:CD6:966F:8156:F87B (talk) 03:30, 23 April 2015 (UTC)edited for spelling and homophones by Wendy Neumeyer Silicon dioxide is insolble in water where as it can be disolved in HF to produce hydro flouro silisic acid [HSiF6] which is used as itching of glass — Preceding unsigned comment added by (talk) 05:50, 8 December 2020 (UTC)

Reactions of silica[edit]

Please outline some of the basic reactions that silica gel is likely to undergo, especially those relating to the preparation of the products listed in the page. could you also include a method for purifying the silica source into the final silica product.

Please come to my job and do it for me so I can stay at home and throw food at my wall. —Preceding unsigned comment added by (talk) 10:45, 21 February 2008 (UTC)

silicon dioxide do not dissolve in water where as it can be dissolved in hydrogen flouride[common formulae HF] to produce hydrofloro silisic acid [h2sif6] which is used as an agent for itching of glass  — Preceding unsigned comment added by (talk) 05:54, 8 December 2020 (UTC) 

Silica in shampoo[edit]

Isn't it a good thing to have silica in shampoo? But what does it do in it? 02:20, 17 June 2006 (UTC)


As far as I know there is no free silicon in nature, but silicon is in oxidized form; in silicon dioxide (quartz etc.) or in complex oxides with metals (silicates). So there is little to happen (chemically) for silicon in a fire or in a lightning. I removed the fires and strokes of lightning producing silicon dioxide(and fulgurites added there afterwards). --AB-fi 18:29, 11 July 2006 (UTC)

It was badly written. I meant to say that silicon dioxide could be formed naturally from silicates by some high temperature processes. I apologise for lack of thought and poor proof reading. The section is now much improved compared to the time when my sentences were added. Jaraalbe 21:43, 11 July 2006 (UTC)

Silicon dioxide solubility[edit]

How soluble is silicon dioxide? My chemistry teacher told me to always remember nothing is insoluble. That, in water (an excellent solvent) everything disolves a bit. Even gold, plastics and, yup, sand. So whats the figure? It should be included in the table, along with any solvent it dissolves in strongly enough in to be consideded actually quite soluble. I would love to find something that will dissolve the beakers in which it was created! - Jack (talk) 23:53, 7 August 2006 (UTC)

The solubility of silica in water is approximately 0.012 G in 100g, which classifies it as insoluble (120 ppm). 22:42, 3 November 2006 (UTC)
And if you want something that dissolves beakers, try HF. Nasty, nasty stuff. WB_Frontier


Does this material turn into glass when heated? C'uzz i have no idea.

Technically you can as normal sand is used to make glass and sand is mostly made Ou of silicon dioxide Lolcat64 (talk) 04:06, 18 April 2020 (UTC)

silica health benefits[edit]

The Journal of Nutrition, Health, and Aging Vol 11(2) 2007 has a special symposium including an editorial and five articles on emerging data with respect to the health benefits of silica. According to articles, silica is the second most prevalent element after oxygen. Articles refer to compelling data suggesting that silica is essential for health.

Here's a nice summary of medical uses/benefits of silica. Don't know how trustworthy the site is, although it does cite some legitimate sources. If anyone is in the mood of adding this info to the page, please do so. Aurimas 06:44, 12 September 2007 (UTC)


What's supposed to be linked at the MSDS link in the info box? Donald Hosek 23:45, 25 June 2007 (UTC)

Bottled water[edit]

I see that a mention of use in bottled water has been removed following this revision. I'm not sure why it was removed, but I know for sure that silicon dioxide can be found in mineral water (at least the one I drink - Naleczowianka), and it's listed under Mineral Content, so it's probably somewhat significant. 36 mg/L of SiO2 in the mentioned mineral water. I will revert back to the older edit and add additional info if no one minds. Aurimas 08:11, 12 September 2007 (UTC)

Just noticed that it's in fact an undo by Scarian of the previous revision. Any reason why this was removed? Manufactured forms is probably not a good place to put it, I agree. Maybe there's a need to start a new section regarding SiO2 in foods? The first comment on this page already hints at a need for this section. Aurimas 08:17, 12 September 2007 (UTC)
silica is also a selling point of Fiji brand bottled water. Among other claims, the label says "it provides the water's great mouth feel" 00:37, 20 September 2007 (UTC)

SiO2 Most common in crust?[edit]

You'd think that it being the most common compound in the crust would make it notable. Although I'm not really sure of this. Can anyone confirm this?-=Elfin=-341 04:31, 4 October 2007 (UTC)

Actual SiO2 is not as common as that table might suggest (60%); that's a simplified way of expressing all silicon compounds, including a large variety of silicates. To make the point more obvious, note that the table says there is 3% of "Na2O". This represents again many sodium minerals, but in this case there is no pure Na2O at all, since it is very reactive (it is a very strong base). --Itub (talk) 13:21, 21 February 2008 (UTC)

another name for SiOSubscript text[edit]

another name for sioSubscript text is silicon dioxide,silica, or silox they are there scientific names  —Preceding unsigned comment added by (talk) 01:06, 15 March 2008 (UTC) 

Ambiguous statement[edit]

"Inhaling finely divided crystalline silica dust in very small quantities (OSHA allows 0.1mg/m3) over time can lead to silicosis, bronchitis or (much more rarely) cancer, ..."

Does this mean:

  • "Inhaling finely divided crystalline silica dust in very small quantities over time can lead to silicosis, bronchitis or (much more rarely) cancer, ... but the OSHA defines a limit of 0.1mg/m3 below which the risk is minimal.";
  • "Inhaling finely divided crystalline silica dust in very small quantities over time can lead to silicosis, bronchitis or (much more rarely) cancer, ..., even if exposure is below the OSHA 0.1mg/m3 limit.";

—? Cutler (talk) 09:50, 21 April 2008 (UTC)

How safe is ingesting silica in food???[edit]

I came to this article to find out how safe it is to ingest food (or drugs) that have silica as an ingredient. (This applies to a large number of especially drugs, and I just purchased for the first time a diet drink -- in powdered form -- with silica as an ingredient.)

My only concern was that the silica particles might be jagged and irritate my digestive tract. Sure enough, the article confirms this potential hazard:

"Small pieces of silicon dioxide are equally harmless, as long as they are not large enough to mechanically obstruct the GI tract, or jagged enough to lacerate its lining."

Thing is, this powdered product might have been pulverized by people blissfully unaware of what their processing might be doing to the shape of the silica particles, and I'd like to know this is not a risk before using it.

Does anyone have an idea whether jagged silica particles is is a realistic danger for food or drugs that are manufactured with silica as an ingredient?

If so, this would be well worth mentioning in the article.

P.S. Someone asked about the purpose of using silica as an ingredient in food products. My guess is that it has nothing to do with making the product "crunchy" (or if it did, we'd know that jagged silica particles is a real possibility!). Rather, I suspect it's used just as it is in silica gel packets: to keep the powder from becoming moist. (And therefore avoid clumping.)Daqu (talk) 01:00, 6 September 2008 (UTC)

That's exactly what it is used for and is classified as an Anti-caking agent in many food additive lists. This article and most research out there seams to conclude that silica passes through us. I assume that in order to lacerate the lining it would have to be visibly jagged bits, along the lines of the glass splinters you can get embedded in your fingers while picking up a shattered tea cup. So my bet is that swallowing a cup of crushed silica is not the best idea but the pulverized powder, in the amounts present in food products / drug products, is ok.

Silox- is this really a name for silica?[edit]

Silox is often used as a shorthand name for (t-butyl)3SiO. It is the name of an industrial group. Is it also a name for silica? --Axiosaurus (talk) 09:02, 23 October 2008 (UTC)

It appears to be used by some for silicon dioxide deposited from a vapor, Chemical vapor deposition (CVD), in preparing semiconductor devices e.g. [2]. Mikenorton (talk) 09:21, 23 October 2008 (UTC)
In fact it appears to be derived from a trademark of Applied Materials Inc. for their low temperature vapor silica deposition process. In this interview if you're interested [3].Mikenorton (talk) 09:38, 23 October 2008 (UTC)
thanks for that- the ref seems to refer to the process e.g. CVD at atmospheric pressure using (presumably) the trademarked process/equipment, but I have not read the paper just the abstract. IMO silox is a very specific usage and a name used for the passivating oxide film on silicon created using the silox process, and because of the ambiguity with the tert-butyl compound and the fact it is a trademark putting it in the lede with the specious derivation of silox from silex (I would bet that it came from silicon oxide)is questionable.--Axiosaurus (talk) 10:17, 23 October 2008 (UTC)
Removed. BTW I think that silex is in there to explain the origin of 'silica'. Mikenorton (talk) 10:37, 23 October 2008 (UTC)

Melting point of cristobalite[edit]

Moved here from article as conflicts with other references (also secondary) which give 1470 as a transition temperature- --Axiosaurus (talk) 10:20, 11 December 2008 (UTC)

Boiling and melting points are incorrect, according to the CRC 85th edition, which sites SiO2 has having a boiling point of 2950 degrees C and a melting point of 1470 (cristobalite). This is one of several mistakes I have run across on various minerals and compounds. I will try to correct others, soon.--Sherlock rocks (talk) 09:03, 11 December 2008 (UTC)

That CRC boiling point of 2950C is much higher than reported elsewhere; for example NIH gives 2230C here:

While OSHA gives 2447C here:

I have a hard time explaining this wide variation (could the higher CRC number be for chemically pure material rather than naturally occurring silicates?). -- (talk) 23:12, 29 December 2018 (UTC)

silica sand[edit]


Can any one tell me if I can use the sand in my fishpond filter —Preceding unsigned comment added by (talk) 06:24, 25 April 2009 (UTC)

It should not be a problem, as the stuff is chemically inert. The main issue would be the particle size distribution desired for the specific application. Beach sand is fairly coarse grained, in general. -- logger9 (talk) 17:11, 22 October 2009 (UTC)

Acidic, Basic or Amphoteric?[edit]

Can anyone please tel me whether SiO2 is acidic, basic or amphoteric? —Preceding unsigned comment added by Vigneshmanix (talkcontribs) 13:56, 25 November 2009 (UTC)

It is definitely acidic under Lux-Flood definition. --Cubbi (talk) 15:34, 26 November 2009 (UTC)

Info about the chemical as a food additive[edit]

-- (talk) 05:55, 10 April 2010 (UTC)

-- (talk) 05:59, 10 April 2010 (UTC)


The brief paragraph in health effects added in March 09 needs clarification/rewording.

A study which followed subjects for 15 years found that higher levels of silica in water appeared to decrease the risk of dementia. The study found that for every 10 milligram-per-day intake of silica in drinking water, the risk of dementia dropped by 11%.<ref>{{cite journal|doi=10.1093/aje/kwn348|year=2009|author=Rondeau, V; Jacqmin-Gadda, H; Commenges, D; Helmer, C; Dartigues, Jf|title=Aluminum and silica in drinking water and the risk of Alzheimer's disease or cognitive decline: findings from 15-year follow-up of the [[PAQUID cohort]].|volume=169|issue=4|pages=489–96|pmid=19064650|journal=American journal of epidemiology|pmc=2809081}}</ref>

I can't access the reference used for verification. The implication is that 100mg/day intake would reverse dementia -- gimme some. Vsmith (talk) 12:57, 21 May 2010 (UTC)

The paragraph of the article (link) says

The risk of dementia was higher for subjects with a high daily aluminum intake (for intake 0.1 mg/day, adjusted relative risk (RR) = 2.26, P = 0.049; model 5, Table 4). Conversely, an increase of 10 mg/day in silica intake was associated with a reduced risk of dementia (adjusted RR = 0.89, P = 0.036; model 5). No tendency toward a dose response effect for aluminum was apparent (likelihood ratio statistic = 3.52 (3 df), P = 0.32; model 7, Table 4), even though a significant linear relation between aluminum and dementia was obtained in model 6 (for an increase of 0.1 mg/day, adjusted RR for aluminum = 1.28; P = 0.017). Model 6, with aluminum entered as a continuous variable, was slightly better than model 5, in which aluminum was divided into 2 classes (difference in Akaike’s Information Criterion = 1.1). There was no significant interaction between aluminum and silica concentrations.

I have adapted the text, but it may need further tweaking. --Dirk Beetstra T C 13:00, 21 May 2010 (UTC)
That was fast, thanks for the link to the article. Vsmith (talk) 13:22, 21 May 2010 (UTC)
Removed comments under Health Effects which were completely unsupported by any citations of any kind. Citation flag has been set for over 1 full year. — Preceding unsigned comment added by (talk) 14:28, 12 July 2011 (UTC)


I hope i'm not embarrassingly wrong but on checking I think there has been a misunderstanding of how to interpret the SiO2 stoichiometry:

In each of the most thermodynamically stable crystalline forms of silica, on average, only 2 out of 4 of each the vertices (or oxygen atoms) of the SiO4 tetrahedra are shared with others, yielding the net chemical formula: SiO2.[4]

This is entirely wrong as far as I know. In SiO2 all oxygens must be shared between two Si atoms to achieve the stoichiometry. Each O bonded to two Si atoms is effectively makes up 1/2 if we were base SiO2 on the smallest repeating unit, hence all 4 are crosslinked. I've made the appropriate changes anyway- i'm merely commenting on here to draw to attention if i'm wrong. —Preceding unsigned comment added by (talk) 22:12, 22 May 2010 (UTC)


In the introduction, there is a random plug for silica nanosprings. It is out of place in the general context of the introduction and seems to be for nothing more than to promote a group's work. Recommend deletion. (talk) 06:23, 1 February 2011 (UTC)

Indeed. Removed. Materialscientist (talk) 06:27, 1 February 2011 (UTC)

space group number[edit]

alpha-quartz is listed as s.g.#152, whereas says its #154. I don't have access to literature to check at the moment, can anybody confirm? Thanks. (talk) 00:27, 17 December 2011 (UTC)

A superficial answer: No. 152 is P3121 [4] [5]; No. 154 is P3221. These groups are very similar and both assigned to the same form of quartz [6]. (different "enantiomorphs" - "left" and "right" alpha quartz) Materialscientist (talk) 00:51, 17 December 2011 (UTC)

liquid density[edit]

What is molten silicon dioxide's density at melting point? This info should be in the article. UNIT A4B1 (talk) 22:09, 25 April 2012 (UTC)

Melting point depends on the crystalline form. I've added a note above the table for 1950-2200 C. Materialscientist (talk) 07:21, 26 April 2012 (UTC)

The Picture on the left near the top[edit]

This picture shows 4 oxygens!!!! it needs to show 2. (Unless I missed the point of this picture!) Creeper jack1 (talk) 19:13, 1 February 2013 (UTC)


The passage on solubility is confusing, as it says that silica is more soluble than quartz. But elsewhere it is said (correctly) that quartz is a form (in fact, one of the most common forms) of silica. So presumably what is meant is that some other forms of silica are more soluble than quartz, in which case it would be useful to sya which they are. (talk) 22:13, 12 April 2013 (UTC)

Portland cement[edit]

It is stated that silicon dioxide (silica) is a primary ingredient in industrial Portland cement. Is there a source for this? As I understand it Portland cement is manufactured from limestone (calcium carbonate), clay minerals, and gypsum (in that order). If available, a limestone already containing a suitable proportion of clay minerals is used; otherwise, clay is added to the mixture. I am not aware that silica in free form (e.g. sand) is ever added to the mixture. (Of course, silica sand is usually part of the aggregate used in concrete, but not the cement itself.) Clay minerals themselves are complex aluminum-silicate compounds, so I suppose you could say that they contain silica, but I don't think silica would usually be recognisable as a distinct component. (talk) 22:33, 12 April 2013 (UTC)

Portland cement and ceramics in general is an area where our editing crew is technically weak, so your comments are helpful. The main gluing stuff of cement is the clinker, which consists of calcium silicates derived from various clays (aluminosilicates) and lime (calcium oxide source). Other comments or corrections would be very welcome.--Smokefoot (talk) 03:22, 13 April 2013 (UTC)

Contradiction ?[edit]

In the section "Uses", paragraph 4, it is stated that silica is an insulator, but also that it stores electrical charge.

To store charge for electrical use requires both an insulator and conductors to form a capacitor, so is the statement correct ?

An explanation would be appropriate please, any offers ? Darkman101 (talk) 07:54, 20 September 2013 (UTC)

jmol interactive 3D Image[edit]

Hello, here the Jmol interactive 3D Image is irrelevant, because it represents the SiO2 diatomic molecule, not any of the crystalline forms of silica. Do we have the correct one? Nicola.Manini (talk) 17:33, 17 December 2015 (UTC)

Smokefoot removed the |SMILES= input, and the Jmol link is using that input so now Jmol is gone too. -DePiep (talk) 19:58, 17 December 2015 (UTC)

Assessment comment[edit]

The comment(s) below were originally left at Talk:Silicon dioxide/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

Comment(s)Press [show] to view →
The following suggestions were generated by a semi-automatic javascript program, and might not be applicable for the article in question.
  • You may wish to consider adding an appropriate infobox for this article, if one exists relating to the topic of the article. [?] (Note that there might not be an applicable infobox; remember that these suggestions are not generated manually)
  • Per Wikipedia:Manual of Style (numbers), there should be a non-breaking space - &nbsp; between a number and the unit of measurement. For example, instead of 1 kg, use 1 kg, which when you are editing the page, should look like: 1&nbsp;kg.[?]
  • Per Wikipedia:Manual of Style (numbers), please spell out source units of measurements in text; for example, the Moon is 380,000 kilometres (240,000 mi) from Earth.[?] Specifically, an example is 1 kg.
  • Per Wikipedia:Manual of Style (headings), headings generally should not repeat the title of the article. For example, if the article was Ferdinand Magellan, instead of using the heading ==Magellan's journey==, use ==Journey==.[?]
  • Please reorder/rename the last few sections to follow guidelines at Wikipedia:Guide to layout.[?]
  • Please ensure that the article has gone through a thorough copyediting so that it exemplifies some of Wikipedia's best work. See also User:Tony1/How to satisfy Criterion 1a.[?]
You may wish to browse through User:AndyZ/Suggestions for further ideas. Thanks, Wim van Dorst (talk) 22:45, 17 April 2009 (UTC)

Last edited at 22:45, 17 April 2009 (UTC). Substituted at 06:11, 30 April 2016 (UTC)

Silica + Water Eutectic?[edit]

The Plate tectonics article mentions in passing that silica and water form a deep eutectic system. Does some elaboration belong here? I have also placed a similar comment at the talk page at eutectic system. —Theodore Kloba () 14:14, 20 September 2017 (UTC)

Possibly in the Geology section, sure. Be Bold and make any changes you seem fit. Polyamorph (talk) 09:38, 20 April 2018 (UTC)

Misinterpretation maybe[edit]

"as a function of temperature, it peaks around 340 °C.[49]" [49]= which states "The solubility of amorphous silica at the vapor pressure of the solution, from 0° to 250° C, is given by the equation log C = -731/T + 4.52, where C is the silica concentration in mg/kg and T is absolute temperature. The maximum solubility at the vapor pressure of solution is 1660 mg/kg at 340°C, and the extrapolated solubility at the critical point is 890 mg/kg. At a constant pressure of 1034 bars, the solubility of amorphous silica from 0° to °C is given by the equation log C = -8102 + 4.82."

As it says, that is the "maximum solubility at the vapor pressure". The equation is in regards to the vapor pressure. If you look at the data they got the max solubility is actually between 4000 and 7000 PPM (4 g/L and 7 g/L): (mentioned in [49] as "AM-77-051"). --User123o987name (talk) 14:56, 25 March 2020 (UTC)