# To find hardness in Mohrs scale [closed]

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

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

## closed as off-topic by bon, Daniel Griscom, arkaia, Jan Doggen, plannapusDec 19 '16 at 12:51

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• Hello, and welcome to Stack Exchange. This sounds like a homework problem to me; is it? (And, what is "oxide"?) – Daniel Griscom Dec 17 '16 at 15:06
• @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 Dec 17 '16 at 18:09
• 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 Dec 17 '16 at 18:46
• I'm voting to close this question as off-topic because it is a homework question and so should show some effort. – bon Dec 18 '16 at 9:04

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