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2. Metallurgical assay - Wikipedia

   en.wikipedia.org/wiki/Metallurgical_assay

   A 19th-century assay laboratory in Tombstone Courthouse State Historic Park, Arizona. A model of a late 19th-century Canadian seal used to certify the quality of assayed gold. A metallurgical assay is a compositional analysis of an ore, metal, or alloy, usually performed in order to test for purity or quality.

3. Assay office - Wikipedia

   en.wikipedia.org/wiki/Assay_office

   Assay offices are institutions set up to assay (test the purity of) precious metals. This is often done to protect consumers from buying fake items. Upon successful completion of an assay (i.e. if the metallurgical content is found be equal or better than that claimed by the maker and it otherwise conforms to the prevailing law) the assay offices typically stamp a hallmark on the item to ...

4. Assay - Wikipedia

   en.wikipedia.org/wiki/Assay

   An assay (analysis) is never an isolated process, as it must be accompanied with pre- and post-analytic procedures. Both the communication order (the request to perform an assay plus related information) and the handling of the specimen itself (the collecting, documenting, transporting, and processing done before beginning the assay) are pre-analytic steps.

5. Bulk leach extractable gold - Wikipedia

   en.wikipedia.org/wiki/Bulk_leach_extractable_gold

   A large quantity of sample (between 2 and 5 kg) is digested or leached with cold sodium cyanide (NaCN) solution (generally 0.1% NaCN), for one to several days (depending on the assay laboratory involved). The gold is dissolved through its formation of a cyanide complex, which is concentrated through the solvent exchange process into an organic ...

6. Colloidal gold protein assay - Wikipedia

   en.wikipedia.org/wiki/Colloidal_gold_protein_assay

   The colloidal gold protein assay is a highly sensitive biochemical assay for determining the total concentration of protein in a solution (~0.1 ng/μL to 200 ng/μL). [1] It was first described in 1987 by two groups who used commercially available "Aurodye" colloidal gold solutions.

7. Touchstone (assaying tool) - Wikipedia

   en.wikipedia.org/wiki/Touchstone_(assaying_tool)

   This method has been used since ancient times. In modern times, additional tests can be done. The trace will react in different ways to specific concentrations of nitric acid or aqua regia, thereby identifying the quality of the gold: 24 karat gold is not affected but 14 karat gold will show chemical activity.