The modern standard is white unglazed porcelain of the same hardness as quartz. Traditionally a piece of polished black siliceous rock, treated with nitric acid, was used to identify minerals from the quality of the powder le
The modern standard is white unglazed porcelain of the same hardness as quartz. Traditionally a piece of polished black siliceous rock, treated with nitric acid, was used to identify minerals from the quality of the powder left behind by a stone. For 10 points—name this tool used by mineralogists to determine the quality of gold.
The modern standard is white unglazed porcelain of the same hardness as quartz.
{touchstone}