<p>Volcanism+Water=Acid rain is the answer to this question.</p>
<p>And now you all know where the free oxygen came from, it is from the acid.</p>
<p>Mars is believed to have had a similar chemical composition as Earth had during the formation.</p>
<p>If you add water to the atmosphere of Mars now you will make carbonic acid that will continue to form oxides on Mars.</p>

CC BY-SA 4.0
2023-01-19T06:27:31.897Z
2023-01-19T08:23:52.487Z
2023-01-19T08:23:52.487Z
trond hansen
<p>What exactly was it in the ancient Martian atmosphere that made it red? Was it water, molecular oxygen or something else?</p>

CC BY-SA 4.0
2022-10-18T01:14:02.077Z
My attempt at an answer crumbled. I do hope something emerges that stands up.
Oscar Lanzi
CC BY-SA 4.0
2022-10-18T09:28:15.127Z
@OscarLanzi: Don't take badly, you're not the only one who has deleted an answer they have posted here, or on other SE site. Maybe you & I could start the "I deleted at least one of my answers" club. I think the crux of this question is what is the origin of oxygen on Mars that resulted in surface minerals being oxidized? On Earth, the [Great Oxidation Event](https://en.wikipedia.org/wiki/Great_Oxidation_Event) arose from oxygen accumulating in the atmosphere due to *life forms* generation oxygen. Did a similar situation occur on Mars & if not, what is the origin of the oxygen involved?
Fred
CC BY-SA 4.0
2023-01-20T12:34:08.423Z
I guess you could refine your question by asking, 'if it was water, then was it a global ocean or is water vapour in the air over 4.5 Gyrs enough'?
AtmosphericPrisonEscape
<geochemistry><planetary-science><mars>
What oxidised the soil on Mars?
Andykins 
# What oxidised the soil on Mars?

(Asked by: username_0 on 2022-10-16)

What exactly was it in the ancient Martian atmosphere that made it red? Was it water, molecular oxygen or something else?

**Tags:** geochemistry, planetary-science, mars

> **Comments:**
> **username_1**: My attempt at an answer crumbled. I do hope something emerges that stands up.  
> **username_2**: @username_1: Don't take badly, you're not the only one who has deleted an answer they have posted here, or on other SE site. Maybe you & I could start the "I deleted at least one of my answers" club. I think the crux of this question is what is the origin of oxygen on Mars that resulted in surface minerals being oxidized? On Earth, the [Great Oxidation Event](https://en.wikipedia.org/wiki/Great_Oxidation_Event) arose from oxygen accumulating in the atmosphere due to *life forms* generation oxygen. Did a similar situation occur on Mars & if not, what is the origin of the oxygen involved?  
> **username_3**: I guess you could refine your question by asking, 'if it was water, then was it a global ocean or is water vapour in the air over 4.5 Gyrs enough'?  

---

## 1 answers

### Answer by username_4 on 2023-01-19. Score: 1

Volcanism+Water=Acid rain is the answer to this question.

And now you all know where the free oxygen came from, it is from the acid.

Mars is believed to have had a similar chemical composition as Earth had during the formation.

If you add water to the atmosphere of Mars now you will make carbonic acid that will continue to form oxides on Mars.


---

