How much does a shekel of iron weigh?

I Samuel 17:4-7 “A champion named Goliath, who was from Gath, came out of the Philistine camp. His height was six cubits and a span. He had a bronze helmet on his head and wore a coat of scale armor of bronze weighing five thousand shekels; on his legs he wore bronze greaves, and a bronze javelin was slung on his back. The shaft of his spear was like a weaver's beam, and his spear's head weighed six hundred shekels of iron…”

So, what is a shekel? Is an iron shekel different than a gold, silver or bronze shekel? Is it a coin? At the time of David and Goliath it was not a coin. However, later the Bible does refer to a shekel as a coin and the value differed greatly depending on the metal used. The Hebrew word shekel is based on the verbal root for "weighing”. A shekel was a unit of weight used in transactions before the wide use of coins. It can be difficult to pinpoint an exact weight because ancient units varied so much. The value of a shekel varied between regions, time eras and governments. Weights were known to vary anywhere from 7 to 17 grams. We have chosen the conservative weight of .445 oz or 12.9 grams. We can have reasonable confidence in our current day weight conversion of Goliath’s weapon and armor with these numbers.

A Shekel =.445oz. or 12.9 grams

The spear head’s weight is 16lbs 11oz.

Goliath’s scale armor alone weighed at least 125lbs.

https://www.gotquestions.org/sanctuary-shekel.html