# Why does an mercury ore exist as HgS?

Cinnabar($$\ce{HgS}$$) is one of the most common ores of mercury.

Why does it not exist at $$\ce{HgO}$$ or some other such compound?

Is there any reason for why it is so prevalent?

Does it react less with other compounds, or maybe due to some solid structure of HgS having some characteristic property giving it more stability?

I'm seeking an explanation without the mention of free energy, because it doesn't properly explain the phenomenon for me. I understand that cinnabar is abundant in the crust, and my question is why is $$\ce{HgS}$$ so common?

• Because most of the mercury in the world is found in cinnabar. – Nilay Ghosh Jul 24 '20 at 18:46
• I think my question does not convey my query, I'll edit it... – Display_name Jul 24 '20 at 18:48
• Because mercury has quite an affinity towards sulfur So, most of the mercury exist in its sulfide form. – Nilay Ghosh Jul 24 '20 at 18:58
• This is kinda getting outside of scope of the site. For example HgSe could be even more "preferable", but there's very little Se in the world. Why? Probable because nucleosynthesis stuff, which I doubt s particularly on topic here. – Mithoron Jul 24 '20 at 19:02
• – Nilay Ghosh Jul 25 '20 at 3:55

Why $$\ce{HgS}$$ and not $$\ce{HgO}$$?

Because of HSAB. F'x has already answered a previous question of why mercury has propensity towards thiols(or in general sulfur). Quoting the relevant information:

In Pearson's HSAB theory (hard and soft acids and bases), the reason the $$\ce{S-Hg}$$ bond is be stronger than the $$\ce{O-Hg}$$ can be explained because $$\ce{S^2-}$$ is a soft basis and $$\ce{Hg(II)}$$ is a soft acid, making a good fit while $$\ce{O^2-}$$ is harder.

• +1 for the courage to simply state "...no one knows why!" – uhoh Jul 25 '20 at 8:05