Calamine

[jrgpots]

I bought about 5 lbs of calamine clay powder to use in cosmetics creams. It didn't work out too well.  So now I have it for other uses.   Calamine is Fe2OZn.   Has anyone used it in glazes?  If so, please share.

 

Jed

[PeterH]

33 minutes ago, jrgpots said:

Calamine is Fe2OZn. 

Are you certain, and can you give a reference?

Wiki gives two definitions of calamine, for a medication and a mineral.

As a medication https://en.wikipedia.org/wiki/Calamine
Calamine is a combination of zinc oxide and 0.5% ferric oxide (Fe₂O₃).

As a mineral https://en.wikipedia.org/wiki/Calamine_(mineral)
During the early 19th century it was discovered that what had been thought to be one ore was actually two distinct minerals:

• Zinc carbonate ZnCO₃ or smithsonite and
• Zinc silicate Zn₄Si₂O₇(OH)₂·H₂O or hemimorphite.

PS Searches for calamine clay were largely uninformative, although this one for Calamine Powder says it is also known as hemimorphite (i.e. zinc silicate).
https://www.thesoapkitchen.co.uk/calamine-powder
... and then gives a safety data sheet for 99.5% zinc carbonate and 0.5% ferric oxide!

Edited November 4, 2022 by PeterH

[jrgpots]

Fe2O4Zn is what pubchem quotes it to be.  Sorry I dropped the subscript on the Oxygen.   In my research I also found Zinc Carbonate as well as hemimorphite.  The clay was mined in India.  It does not give chemical analysis.   This is all I have.

 

I thought I would heat it up dry to drive off any CO2, leaving the Fe2O2Zn.

 

 

[jrgpots]

I will try it and find out.

 

[PeterH]

5 hours ago, jrgpots said:

Fe2O4Zn is what pubchem quotes it to be. 

Don't you just love it when they overload an already overloaded name.

Personally I find the Pubchem page https://pubchem.ncbi.nlm.nih.gov/compound/Calamine massively confusing as it gives Calamine lotion as a synonym. At least here in the UK Calamine lotion BP (British Pharmacopea) is zinc oxide with 0.5% ferric oxide -- and has been at least since at least the 1950s when it was widely used to treat sunburn. 

Anyway, what colour is the stuff you have? American Elements https://www.americanelements.com/zinc-iron-oxide-12063-19-3 give Fe2O4Zn as Zinc Iron Oxide (aka Zinc Ferrite) a brown solid.
There is a picture at https://www.funcmater.com/zinc-iron-oxide-znfe2o4-powder.html

While calamine powder BP (the 99.5% zinc oxide, 0.5% ferric oxide stuff) is decidedly pink
https://m.jppharmaglobal.com/calamine-powder-bp-5307563.html

While both pure zinc carbonate and pure zinc silicate are white
 

[jrgpots]

Mine is the pink powder.   It is really hard to know exactly what it is!  I will calcine about 500 GM of the stuff and see what happens.  I will compare it to Zn oxide in a side by side recipe  with the calamine.  Maybe opacity a celadon  and see it there is a color change because of the Fe.

Jed

[Min]

Interesting! Would also be interesting to see what happens to fire it in your new kiln under reduction, depending on how hot you get there might be nothing but some of the iron left. Maybe fused a bit with whatever it's being fired on? 

[PeterH]

19 hours ago, jrgpots said:

Mine is the pink powder.   It is really hard to know exactly what it is!  I will calcine about 500 GM of the stuff and see what happens.  I will compare it to Zn oxide in a side by side recipe  with the calamine.  Maybe opacity a celadon  and see it there is a color change because of the Fe.

Jed

I'm pretty certain its mainly zinc oxide with a little ferric oxide. Probably quite close to calamine powder BP (the 99.5% zinc oxide, 0.5% ferric oxide). After all it is a skin treatment with a long pedigree.