How to grow a crystals with gypsum and other materials?

Dear: Instructables

Just to let you know I am limited to materials in my house. I want to grow a crystal with plaster like plaster of Paris but I am running into a few problems. I know that Gypsum or plaster of Paris is already a crystal but it doesn't have the necessary hardness I want. I want It to have a hardness of a minimum of 6 on the Mohs's scale. I also am limited to chemistry knowledge. I've been trying all day to design a crystal with the specifications I want but I've been having trouble trying to draw a Lewis dot diagram for plaster of Paris. I am not that good at drawing Lewis dot diagrams unfortunately. Here are some materials in my house I think I could use to incorporate with the homemade crystals.


Potassium Chloride


Baking Soda

Potassium Nitrate

and more...

Can I have some help please? Thank you.

From: Noah

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It is clear that you don't even know enough to get yourself into trouble here so I'm going to say that you don't have a hope of making a crystal. Not just crystals with a hardness >6, but all crystals. Not even sugar crystals.

nschreiber0813 (author)  The Ideanator1 year ago

What the heck? I have watched tutorials on this site for making crystals and stuff. You saying I have no hope is kinda derogatory no offence because you clearly have no reason. Do you have a reason?

I have my reasons. Plaster of paris(anhydrous calcium sulfate + additives) is not gypsum(calcium sulfate dihydrate), it is a cooked form of it. When you rehydrate it, it does the whole plaster thing.
Acetone crystallizes at -95°C (dry ice is about −78.5 °C)
KCl is about a mohs 2.5
Sugar is less than that
NaHCO3 is 2.5
KNO3 is a 2
All of the materials that I'm aware of with a minimum hardness of 6 fall into about 3 categories:
- easy to make and doesn't form crystals, things like steel and nickel.
- hard to make and forms tiny crystals, things like the druzy crusts on your crucible or reaction vessel, analagous to the seed crystals in those evaporation methods
- extremely hard to make and could form decent crystals, quartz and feldspar are close to 6 and are probably what you're thinking of. This is how they grow quartz for the electronics industry.
All of them are well beyond the manufacturing capabilities of a decent home lab. I wish you luck, but I would recommend screwing around with easier things like metal salts first. If you do want to do something that doesn't require high heat and pressure, I'd recommend looking into what chemists call "recrystalization". The sciencemadness forums are full of pretty crystals if you wish to go that route instead.

nschreiber0813 (author)  The Ideanator1 year ago

Okay thank you I will check it out.

If you did so much research then I guess nobody here can understand your problem.
You mix terms and topics like it does not matter.
If you want a hard crystal then for god's sake you have to start growing a hard crystal and not a soft one.
To build y house do you use balsa wood and try to harden it once the frame for the house is up or do you just just the right wood instead? ;)

nschreiber0813 (author)  Downunder35m1 year ago

Okay thank you and sorry. I'll do some research!!!

What kind of stuff has a 6 hardness already? How is it formed and what chemicals are they composed of? Lots of heat and pressure are needed to form diamonds.

nschreiber0813 (author)  caitlinsdad1 year ago

Wait why does it matter what stuff already has a hardness of 6? Also why does it matter how it is formed and what chemicals it is made of and which stuff are you referring to about this? Also who said anything about diamonds? I am not trying to make anything with a hardness of 10 over here.

It seems you have no real clue about what you are actuall doing, how crstal are formed and what defines the hardness of a material.
To say it nice: Take a marshmallow and make it as hard as solid oak - without freezing it or cheats like that.
You ask how to change the chemical and physical properties of a substance to make it harder - guess what, after that it is not the same substance anymore.

Do yourself a favour and read up on the projects you start so you know what it is about and how it works.
If you want a hard crystal then you select a base material that will form a hard crystal and not one that is soft as a fart ;)

nschreiber0813 (author)  Downunder35m1 year ago

Well at this point I think I am just going to follow a tutorial for crystal making. I've been trying to design my own crystals and I don't think that is a good idea with my expereince. Thank you.

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