<p>Although this is a somewhat poorly researched question, I think there is an opportunity to make a nice point here.</p>

<p>First of all, let's look at the Mohs scale:</p>

<ol>
<li><p>Talc</p></li>
<li><p>Gypsum</p></li>
<li><p>Calcite</p></li>
<li><p>Fluorite</p></li>
<li><p>(fluor)Apatite</p></li>
<li><p>K-Feldspar</p></li>
<li><p>Quartz</p></li>
<li><p>Topaz</p></li>
<li><p>Corundum</p></li>
<li><p>Diamond</p></li>
</ol>

<p>Their (<em>simplified</em>) chemical formulae are:</p>

<ol>
<li><p>$\ce{Mg3Si4O10(OH)2}$</p></li>
<li><p>$\ce{CaSO4\cdot2H2O}$</p></li>
<li><p>$\ce{CaCO3}$</p></li>
<li><p>$\ce{CaF2}$</p></li>
<li><p>$\ce{Ca5(PO4)3F}$</p></li>
<li><p>$\ce{KAlSi3O8}$</p></li>
<li><p>$\ce{SiO2}$</p></li>
<li><p>$\ce{Al2SiO4F2}$</p></li>
<li><p>$\ce{Al2O3}$</p></li>
<li><p>$\ce{C}$</p></li>
</ol>

<p>What are the anionic groups in each mineral? These are the anions that the metallic cations bond to in the mineral. Let's see:</p>

<ol>
<li><p>$\ce{Si4O10(OH)2}$ : hydrous silicate</p></li>
<li><p>$\ce{SO4}$ : sulfate</p></li>
<li><p>$\ce{CO3}$ : carbonate</p></li>
<li><p>$\ce{F2}$ : halide (fluoride)</p></li>
<li><p>$\ce{(PO4)3F}$ : phosphate-fluoride</p></li>
<li><p>$\ce{Si3O8}$ : silicate</p></li>
<li><p>$\ce{SiO2}$ : silicate (although can be regarded as oxide, but it has the silicate framework)</p></li>
<li><p>$\ce{SiO4F2}$ : silicate-fluoride</p></li>
<li><p>$\ce{O3}$ : oxide</p></li>
<li><p>$\ce{C}$ : covalently bonded carbon, no anions here</p></li>
</ol>

<p>This should help you find the correct answer.</p>

<p>However, this is only relevant for the Mohs scale. This does not mean, for example, that all oxides are harder than all silicats. Magnesium oxide is pretty soft, for example.</p>

CC BY-SA 3.0
2016-12-18T07:37:05.453Z
2016-12-18T07:37:05.453Z
Gimelist
<p>Except diamondת which mineral is having high hardness in Mohr scale.  </p>

<ul>
<li>A Oxide</li>
<li>B silicate</li>
<li>C carbonate</li>
<li>D phosphate</li>
</ul>

CC BY-SA 3.0
2016-12-17T15:06:55.777Z
Hello, and welcome to Stack Exchange. This sounds like a homework problem to me; is it? (And, what is "oxide"?)
Daniel Griscom
CC BY-SA 3.0
2016-12-17T18:09:22.113Z
@DanielGriscom  this question was asked in IIT geology exam and i have no idea with the option, as i know after diamond , corundum is hardest. Can you please tell me the answer on the basis of option.?
Girish Kumar Chandora
CC BY-SA 3.0
2016-12-17T18:46:33.733Z
I doubt you'll get a good answer here, but I bet if you Google "table of mohr hardnesses" you'll get what you want.
Daniel Griscom
CC BY-SA 3.0
2016-12-18T09:04:35.003Z
I'm voting to close this question as off-topic because it is a homework question and so should show some effort.
bon
<geology><mineralogy><homework><crystallography>
To find hardness in Mohrs scale
Girish Kumar Chandora
# To find hardness in Mohrs scale

(Asked by: username_0 on 2016-12-17)

Except diamondת which mineral is having high hardness in Mohr scale.

* A Oxide
* B silicate
* C carbonate
* D phosphate

**Tags:** geology, mineralogy, homework, crystallography

> **Comments:**
> **username_1**: Hello, and welcome to Stack Exchange. This sounds like a homework problem to me; is it? (And, what is "oxide"?)  
> **username_0**: @username_1  this question was asked in IIT geology exam and i have no idea with the option, as i know after diamond , corundum is hardest. Can you please tell me the answer on the basis of option.?  
> **username_1**: I doubt you'll get a good answer here, but I bet if you Google "table of mohr hardnesses" you'll get what you want.  
> **username_2**: I'm voting to close this question as off-topic because it is a homework question and so should show some effort.  

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## 1 answers

### Answer by username_3 on 2016-12-18. Score: 4 | Accepted answer

Although this is a somewhat poorly researched question, I think there is an opportunity to make a nice point here.

First of all, let's look at the Mohs scale:

1. Talc
2. Gypsum
3. Calcite
4. Fluorite
5. (fluor)Apatite
6. K-Feldspar
7. Quartz
8. Topaz
9. Corundum
10. Diamond

Their (*simplified*) chemical formulae are:

1. $\ce{Mg3Si4O10(OH)2}$
2. $\ce{CaSO4\cdot2H2O}$
3. $\ce{CaCO3}$
4. $\ce{CaF2}$
5. $\ce{Ca5(PO4)3F}$
6. $\ce{KAlSi3O8}$
7. $\ce{SiO2}$
8. $\ce{Al2SiO4F2}$
9. $\ce{Al2O3}$
10. $\ce{C}$

What are the anionic groups in each mineral? These are the anions that the metallic cations bond to in the mineral. Let's see:

1. $\ce{Si4O10(OH)2}$ : hydrous silicate
2. $\ce{SO4}$ : sulfate
3. $\ce{CO3}$ : carbonate
4. $\ce{F2}$ : halide (fluoride)
5. $\ce{(PO4)3F}$ : phosphate-fluoride
6. $\ce{Si3O8}$ : silicate
7. $\ce{SiO2}$ : silicate (although can be regarded as oxide, but it has the silicate framework)
8. $\ce{SiO4F2}$ : silicate-fluoride
9. $\ce{O3}$ : oxide
10. $\ce{C}$ : covalently bonded carbon, no anions here

This should help you find the correct answer.

However, this is only relevant for the Mohs scale. This does not mean, for example, that all oxides are harder than all silicats. Magnesium oxide is pretty soft, for example.


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