Metal’s prices volatility causes various gold rushes or exploration push creating the need XRF instruments for quickly obtain metal/gold assays. From pawn brokers to jewels and precious metals recyclers. Be sure to be armed with a XRF instruments to not be fooled. XRF instruments are fast, easy to use and precise.  Below is a comparative table for gold assay methods, accuracy and price.

Compare_Gold_Analysis_Techniques_-_Methods

http://www.folioinstruments.com/faq/faq%20oxford/real%20word%20accuraracy%20of%20xrf.pdf

Here a good paper on gold assay methods compared.