Well, I remember when i was a child, i used to take water and sugar and mix it in a jar, then i would tie a peice of string around a stick then place the stick horizontally over the top of the jar, and let the string dangle into the sugar water. After the watter evaporated there would be sugar crystals. I'm not sure if this will work but its worth a try! :) Hope this helps!
Crystal size in these rock types is determined by their rate of cooling. Pegmatites have large crystals due to very slow cooling. Obsidian has microscopic crystals due to almost instantaneous cooling.
intrusive followed by an extrusive phase
No, because intrusive rocks form underneath the earth and cool very slowly which causes larger minerals and extrusive rocks form above the ground which cool very rapidly which causes very small minerals. so i hope you get it. Now I'm done.
It varies some metamorphic rocks are fine grained (eg slate) and others have very large crystals (eg an augen gneiss).
When molten rock cools slowly, it will have a lot of time to form crystals, so the crystal size will be quite big. Take granite, for example. With the naked eye, you can see the individual crystals. The grain size is quite large. The kind of mineral that forms is dependent on the composition of the magma.
The smaller crystals have more surface area exposed to be dissolved. Since the larger crystal has a bigger volume to surface area ratio, it will take longer to dissolve it all.
The will be large in an extrusive granite and fine in an intrusive basalt.
Crystal size in these rock types is determined by their rate of cooling. Pegmatites have large crystals due to very slow cooling. Obsidian has microscopic crystals due to almost instantaneous cooling.
intrusive followed by an extrusive phase
There are numerous physical properties of table sugar. Some of these include being colorless, odorless, fine, sweet tasting, and a type of powder that contains crystals.
Fine grained has larger crystals and coarse grained has smaller crystals
Fine grained has larger crystals and coarse grained has smaller crystals
The type of igneous rock that has large crystals surrounded by smaller crystals is not a rock but a porphyritic texture. This texture describes igneous rock that has porphyrites, or large crystals, with surrounding tiny particles, or groundmass.
Rarity is relative. My experience and a quick perusal of mindat.org would suggest that jarosite is not very rare. (There are many hundreds of localities, and fine micro crystals can be easily purchased for a few bucks.) However, jarosite is indeed rare in large crystals or fine specimens of display quality.
extrusive
Groundmass
The smallest aperatures flax seed grinder approaches near dust size results. It is amazing what they are capable of.