Investors interested in stocks from the Mining - Miscellaneous sector have probably already heard of Impala Platinum Holdings Ltd. (IMPUY) and Wheaton Precious Metals Corp. (WPM). But which of these two stocks offers value investors a better bang for their buck right now? We'll need to take a closer look.There are plenty of strategies for discovering value stocks, but we have found that pairing a strong Zacks Rank with an impressive grade in the Value category of our Style Scores system produces the best returns. The proven Zacks Rank puts an emphasis on earnings estimates and estimate revisions, while our Style Scores work to identify stocks with specific traits.Currently, Impala Platinum Holdings Ltd. has a Zacks Rank of #2 (Buy), while Wheaton Precious Metals Corp. has a Zacks Rank of #3 (Hold). This means that IMPUY's earnings estimate revision activity has been more impressive, so investors should feel comfortable with its improving analyst outlook. But this is just one factor that value investors are interested in.Value investors are also interested in a number of tried-and-true valuation metrics that help show when a company is undervalued at its current share price levels.The Value category of the Style Scores system identifies undervalued companies by looking at a number of key metrics. These include the long-favored P/E ratio, P/S ratio, earnings yield, cash flow per share, and a variety of other fundamentals that help us determine a company's fair value.IMPUY currently has a forward P/E ratio of 5.60, while WPM has a forward P/E of 31.19. We also note that IMPUY has a PEG ratio of 0.99. This popular metric is similar to the widely-known P/E ratio, with the difference being that the PEG ratio also takes into account the company's expected earnings growth rate. WPM currently has a PEG ratio of 6.24.Another notable valuation metric for IMPUY is its P/B ratio of 1.70. Investors use the P/B ratio to look at a stock's market value versus its book value, which is defined as total assets minus total liabilities. By comparison, WPM has a P/B of 3.20.Based on these metrics and many more, IMPUY holds a Value grade of A, while WPM has a Value grade of D.IMPUY sticks out from WPM in both our Zacks Rank and Style Scores models, so value investors will likely feel that IMPUY is the better option right now. Breakout Biotech Stocks with Triple-Digit Profit Potential The biotech sector is projected to surge beyond $2.4 trillion by 2028 as scientists develop treatments for thousands of diseases. They’re also finding ways to edit the human genome to literally erase our vulnerability to these diseases. Zacks has just released Century of Biology: 7 Biotech Stocks to Buy Right Now to help investors profit from 7 stocks poised for outperformance. Recommendations from previous editions of this report have produced gains of +205%, +258% and +477%. The stocks in this report could perform even better.See these 7 breakthrough stocks now>>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Impala Platinum Holdings Ltd. (IMPUY): Free Stock Analysis Report Wheaton Precious Metals Corp. (WPM): Free Stock Analysis Report To read this article on Zacks.com click here.