Sciencemadness Discussion Board

Telling apart Potash from Cinnabar

yeah - 28-7-2017 at 21:51

May have pulverized two ore together in a mortar.
Both can be distinct, potassium ore forming crystals. Sometimes these can grow to a deeper red.
Trying to form Mercuric Oxide and Potassium Chloride separately.

ave369 - 31-7-2017 at 06:06

Cinnabar is red. Potash has no color. That's how you tell them apart.

yeah - 1-8-2017 at 15:07

In these bits of crystalline potassium chloride the crystalline structure varies between Red, white, yellow and pink. Sometimes some bits aren't sylvinite or potash and are a purple-ish amalgam semi-crystalline. Some bits of cinnabar [not crystalline in nature] exist on separate ore and are solid smooth deep red.

None of the ore with cinnabar has crystalline potassium, in fact some cinnabar aren't smooth and solid but are infact infused into a rock, turning a whole rock ore a red tint.

If I wish to separate Mercury[II] Oxide and potassium for a electrolysis experiment, I should just be able to dissolve the potassium in brine, electrolyse it and separate from sodium with a freeze chest.
I wonder what other forms of mercury may be in the ore, and how easily soluble the KCl is, because I already panned it out once to remove sand and other dirt impurities.

ave369 - 1-8-2017 at 15:50

Quote: Originally posted by yeah  
In these bits of crystalline potassium chloride the crystalline structure varies between Red, white, yellow and pink.


1. Potash is potassium carbonate, not potassium chloride.
2. All colored varieties of potassium chloride are technical grade. Recrystallize them and find out that potassium chloride actually has no color.

yeah - 1-8-2017 at 20:48

Can you cite anything? I'm no cook, just learning about natural sources.

macckone - 1-8-2017 at 21:37

potassium carbonate is quite soluble in water.
potassium chloride is even more soluble.
mercuric oxide is not readily soluble.
mixing with water will selectively dissolve the potassium salts.

yeah - 1-8-2017 at 22:09

Electrolysis of this solution produces Hydroxides of these salts. Is there a way to eliminate impurities or purify the KCl or KOH?

I've seen someone pan Mercuric Oxide, I will have to pulverize it to a finer powder so it stands out as it's heavy insoluble oxide. If done right, I can afford a reasonably pure red HgO. I can seal it tight until I learn if I will be doing any reactions with it.

phlogiston - 1-8-2017 at 22:41

Cinnabar is mercury(II)sulfide, not HgO

AJKOER - 2-8-2017 at 07:35

Add an acid, say acetic acid.

The sulfide forms H2S (strong rotten egg odor which is toxic).

The carbonate yields CO2.

Heat the dry salt to decomposition outdoors (still use protective breathing equipment as Hg fumes are toxic).

Breakup the solid mass forming powder.

Add hot water. You now could have a soluble solution of KOH and insoluble HgO.

However, you may just make an insoluble messy glob or rock. So do a small scale test run first!

[Edited on 2-8-2017 by AJKOER]

unionised - 2-8-2017 at 09:49

Quote: Originally posted by AJKOER  
Add an acid, say acetic acid.

The sulfide forms H2S (strong rotten egg odor which is toxic).

The carbonate yields CO2.

Heat the dry salt to decomposition outdoors (still use protective breathing equipment as Hg fumes are toxic).

Breakup the solid mass forming powder.

Add hot water. You now could have a soluble solution of KOH and insoluble HgO.

However, you may just make an insoluble messy glob or rock. So do a small scale test run first!

[Edited on 2-8-2017 by AJKOER]

Quite a lot of that is simply wrong.
Many sulphides will react with acids to form H2S- but HgS is too insoluble to react. Acetic acid will definitely fail.

Heating potassium compounds will not generally give the oxide- the equilibrium is never really favourable.
Potash is generally produced in fires- if heating it made it decompose to the oxide then leaching wood ash wouldn't give a solution of the carbonate

yeah - 2-8-2017 at 10:19

I have an understanding of calcium carbonates, but the mineral KCl I don't understand what occurs when it is heated. I would rather like to find the properties of KCl and K2CO3, since the settling of the panning water has left a fine light tan powder on the bottom.

AJKOER - 3-8-2017 at 03:58

Yes, I agree some issues.

I should have stated more precisely that the active reagents are upon boiling outdoors are O2 and acetic acid. Best if ones adds a touch of sea salt (or in the case of mercury salts, better would be KNO3). The latter NaCl (and other trace compounds), or KNO3, serves actually as an electrolyte in this electrochemical dissolution process. There is no issue with following this recipe with preferrably diluted H2O2 in place of air with silver metal (as I have successfully done using periodic microwave treatments in preparing silver acetate in just a few hours using KNO3 in lieu of NaCl due to solubility issues with AgCl, please see discussion and links at http://www.sciencemadness.org/talk/viewthread.php?tid=69061#... , but microwaving cannot, for safety and contamination issues, be done with Hg salts).

However, I am guessing that an electrochemical approach actually works with HgS (but it does for HgO, see https://en.m.wikipedia.org/wiki/Mercury_battery ) but I have no experience, as I avoid mercury salts in general.

Note, a spontaneous electrochemical method works for cleaning silver tarnish (in essence, attacking silver sulfide).

One can also try a direct standard chemical attack with concentrated Oxalic acid on HgS, but I would, per experience, expect even dilute H2C2O4, 3% H2O and a touch of KNO3 to be more effective!

[Edited on 3-8-2017 by AJKOER]

fusso - 14-4-2018 at 09:49

Quote: Originally posted by yeah  
Electrolysis of this solution produces Hydroxides of these salts. Is there a way to eliminate impurities or purify the KCl or KOH?

I've seen someone pan Mercuric Oxide, I will have to pulverize it to a finer powder so it stands out as it's heavy insoluble oxide. If done right, I can afford a reasonably pure red HgO. I can seal it tight until I learn if I will be doing any reactions with it.


Ohh you can get Hg minerals from panning?! I thought only Au & Fe3O4 are present in the final batches of panned material! How much HgO/HgS could you get from that? Is HgO/HgS present in appreciable amount in any Au containing areas or are they only from certain specific places?

DraconicAcid - 14-4-2018 at 10:54

Quote: Originally posted by ave369  
Quote: Originally posted by yeah  
In these bits of crystalline potassium chloride the crystalline structure varies between Red, white, yellow and pink.


1. Potash is potassium carbonate, not potassium chloride.
2. All colored varieties of potassium chloride are technical grade. Recrystallize them and find out that potassium chloride actually has no color.


Technically true, but in Saskatchewan, they mine a lot of potassium-containing minerals and call them all potash (even the chloride).

elementcollector1 - 14-4-2018 at 11:05

Any sufficiently heavy minerals can be panned. In fact, I've panned for garnets more than once, and their density is just a measly 4 g/cc compared to gold's 19.3 and mercuric oxide's 11.14.