As silver in a crucible and gold in a pan, so our lives are assayed by God. (Proverbs 17:3)
Silver is mined - then must be separated from all the various impurities that it is surrounded by such as sulfur, arsenic, antimony, chlorine, or argentite - all important elements, but not really desirable for us to wear or use in our eating utensils! It is rarely found in some big clump, or small dust particles such as you have with gold. There is a refining process that must occur in order to separate the other stuff from the silver so you are left with the silver alone. Silver is 'bound to' or 'clings to' other substances and it must be 'extracted' from the stuff that it clings to or that which clings to it.
Sulfur - when burned, it can have a suffocating odor. Its various uses are for the production of gunpowder, in the formulation of medicines to kill various germs, and in the vulcanizing process of making rubber. While it has a benefit to us, it doesn't really belong to the silver, nor is the silver made any stronger by it being there.
Arsenic - the interesting thing about arsenic is that it vaporizes when heated, has a great metallic luster which gives it an appearance of beauty, and is quite poisonous if it is ingested. Now, I don't know about you, but something that that just gives me an appearance of beauty, but is 'poisonous' by nature isn't all that appealing! I don't think we'd want that stuff around too long!
Antimony - a kind of lustrous metal compound that looks good, but has very little value as a metal. It has one main use as an addition to metal alloys to give them strength. It is the item usually added to the mix when someone is manufacturing semi-conductors. The important thing to remember is that it is quite toxic - although useful, it carries a very high risk by being present.
Chlorine - we know that chlorine has many uses, but its main use is in the purification process because it has the ability to kill bacteria. It is toxic in both its gaseous and more "visible" forms such as liquid or crystal. Sometimes it is a silent killer since it can escape without notice and be carried pretty far on the winds. There is really a great risk in keeping something so volatile and lethal around.
Argentite - this mineral usually never exists alone. It is found in the silver mines along with the silver, clinging to the silver as part of the ore. It is lead grey in color and is very unstable once exposed to air, so it is not really of any use as a mineral. It is a 'cling-on', but it is useless if it cannot 'ride on' something else. Remove it and the silver is still strong - keep it around and it just makes silver ugly.
Okay, I did not want to bore you with all kinds of information on the minerals of silver mining, but I wanted to refer to each of these just a little bit to bring some clarity to why this analogy of silver in a crucible is used to describe God's work in our lives. It is important for us to see just what God may be doing by placing us in circumstances that we refer to as the furnace - the refining "crucible" of trial.
We may have some "sulfur-like" behavior that we need to have brought to the surface and separated from our lives - such as anger or wrath. When it is allowed to remain "combined" with the silver - we have a "combustible" part of our character that does not bring honor to God. Arsenic may look good, adding some type of "luster" to our character, but it is toxic. We might have some types of "toxic" character traits, such as gossip, malice, or envy that God knows have the capacity to be extremely "toxic" if they are allowed to remain. He puts us through the purifying process in order to remove these from our lives.
Antimony gives the appearance of "looking good", but the presence of the "mask" never determines the reality of what is hidden. God knows that a transparent Christian is more valuable than one that looks good on the outside and is hiding nothing of value on the inside. Antimony is kind of like being this intensely strong appearing Christian on the outside, but being a blubbering idiot on the inside!
Chlorine has both a positive and negative affect - it can be a purifying agent, but not until it is "processed". It must be separated from all the other impurities, then it has to be used very carefully or it burns! We can liken this to either giving off a "sweet smelling odor" that delights God, or being "toxic" in what we emanate, burning the world around us. Argentite is absolutely worthless when it is exposed to air - it does nothing to lend to the strength or beauty of the silver once it is exposed. That is the same with any secret sin in our lives - as long as it is hidden in the core of our inner man, it gets along just fine. Once exposed to the Word of God, the sin shows the true corruptibility of its presence. God always uses the furnace and crucible of circumstance (trial) to remove the stuff that only serves to contaminate our spiritual beauty and our testimony. The next time you are going through the fire, you might ask God what "worthless mineral" he is focusing on separating from your life at that moment in time. The "smelting" process God uses is designed to produce the clarity of pure, refined silver - gleaming in all its beauty, reflective of the image of Jesus. Just burnin!