Below are the top small-cap nonmetallic mineral mining stocks on the NYSE, the NASDAQ and the AMEX in terms of operating margin.

The trailing-twelve-month operating margin at L&L Energy Inc (NASDAQ: LLEN) is 21.89%. LLEN's ROE for the same period is 33.10%.

The trailing-twelve-month operating margin at Rhino Resource Partners LP (NYSE: RNO) is 9.73%. RNO's revenue for the same period is $329.75 million.

The trailing-twelve-month operating margin at Harry Winston Diamond Corporation (NYSE: HWD) is 8.18%. HWD's PEG ratio is 0.31.

The trailing-twelve-month operating margin at China GengSheng Minerals Inc (AMEX: CHGS) is 2.17%. CHGS' revenue for the same period is $71.95 million.

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