It is sometimes stated that singing bowls are 'traditionally' made of an alloy consisting of various metals, often seven, each associated with a heavenly body. Those commonly mentioned are gold, silver, mercury, copper, iron, tin and lead (or antimony). This is said to be supported by the results of a 1996 analysis of two bowls by Concordia University, which found them to be essentially of bell metal with small quantities—consistent with impurities—of some of the other metals that were looked for, namely lead, zinc, iron and silver. No gold or mercury was found within the accuracy of the measuring apparatus.