Reaction in a crucible resulting in formation of crystals

[Cmpope]

Yesterday i was melting stuff in an iron "crucible" for no specific reason. Today I was surprised to have found several different types of crystals growing on top of some silver metal I had left in the crucible the day before. What I'm wondering now is what exactly can this possibly be? In order to get an idea of what it could be I will list everything that has been melted/burned in it:

Copper Powder

Bismuth

Silver

Magnesium

Borax

When I most recently melted stuff in it with a propane torch, the crucible became a glowing hot orange color. Any ideas of what these might be? Also I'm new to this forum and I hope I am actually asking this in the right place, I don't know where to get help for this kind of thing. 

 

[Sensei]

Air contains water,

Air contains Oxygen.

Air contains Carbon Dioxide..

If you leave some melted metal or alloy unprotected against the above three (at least), they can react with them..

 

e.g. Magnesium reacts with Oxygen, and MgO can react with CO₂ (with eventual bicarbonate route), giving MgCO₃

 

Edited June 9, 2018 by Sensei