This week, the ratings of 15 Metals and Mining stocks on Portfolio Grader are down. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

This week, Banro Corp. (AMEX:BAA) falls to a D (“sell”), worse than last week’s grade of C (“hold”). Banro Corporation is engaged in the exploration and development of four gold properties, which are known as Twangiza, Namoya, Lugushwa and Kamituga. In Portfolio Grader’s specific subcategories of Earnings Revisions, Equity, and Cash Flow, BAA also gets an F. For a full analysis of BAA stock, visit Portfolio Grader.

Barrick Gold (NYSE:ABX) ratings are on the decline this week as the company earns an F (“strong sell”). Last week, it received a D (“sell”). Barrick Gold makes and sells gold, and is involved with related activities such as exploration and mine development. The stock also rates an F in Earnings Surprise. ABX shares are down 2.9% since last month. This is worse than the S%P 500’s 4.8% increase for the same period. For more information, get Portfolio Grader’s complete analysis of ABX stock.

This week, Goldcorp‘s (NYSE:GG) rating worsens to an F from the company’s D rating a week ago. Goldcorp acquires, explores, develops, and operates precious metal properties. The stock also gets an F in Sales Growth. To get an in-depth look at GG, get Portfolio Grader’s complete analysis of GG stock.

The rating of AMCOL (NYSE:ACO) declines this week from a C to a D. AMCOL International is a specialty minerals company that offers various industrial and consumer product lines. For a full analysis of ACO stock, visit Portfolio Grader.

The rating of Yamana Gold (NYSE:AUY) slips from a C to a D. Yamana Gold is a gold producer with significant gold production, gold development stage properties, exploration properties, and land positions in Brazil, Chile, Argentina, Mexico, and Colombia. The stock gets F’s in Earnings Growth, Earnings Surprise, and Sales Growth. For more information, get Portfolio Grader’s complete analysis of AUY stock.

Allied Nevada Gold (AMEX:ANV) is having a tough week. The company’s rating falls from a D to an F rating. Allied Nevada Gold engages in the evaluation, acquisition, exploration, and advancement of gold exploration and development projects. The stock gets F’s in Earnings Momentum, Earnings Revisions, and Earnings Surprise. The stock’s trailing PE Ratio is 48.9. To get an in-depth look at ANV, get Portfolio Grader’s complete analysis of ANV stock.

New Gold Inc.‘s (AMEX:NGD) rating weakens this week, dropping to a D versus last week’s C. New Gold acquires, explores, and develops gold properties. The stock has a trailing PE Ratio of 26.7. For a full analysis of NGD stock, visit Portfolio Grader.

Endeavour Silver (NYSE:EXK) earns a D this week, moving down from last week’s grade of C. Endeavor Silver is a small-cap silver mining company focused on the growth of its silver production, reserves and resources in Mexico. The stock gets F’s in Earnings Momentum, Earnings Revisions, and Earnings Surprise. The trailing PE Ratio for the stock is 26.3. To get an in-depth look at EXK, get Portfolio Grader’s complete analysis of EXK stock.

This is a rough week for China Gerui Advanced Materials (NASDAQ:CHOP). The company’s rating falls to D from the previous week’s C. China Gerui Advanced Materials engages in the manufacture and sale of cold-rolled narrow and wide strip steel products in the People’s Republic of China. The stock price has dropped 16.2% over the past month. For more information, get Portfolio Grader’s complete analysis of CHOP stock.

Seabridge Gold (NYSE:SA) experiences a ratings drop this week, going from last week’s D to an F. Seabridge Gold acquires gold projects in North America. The stock gets F’s in Equity and Cash Flow. For a full analysis of SA stock, visit Portfolio Grader.

Globe Specialty Metals (NASDAQ:GSM) earns an F this week, falling from last week’s grade of D. Globe Specialty Metals produces silicon metal and silicon-based alloys, which are used in a variety of industrial and consumer products. The stock gets F’s in Earnings Momentum and Earnings Surprise. To get an in-depth look at GSM, get Portfolio Grader’s complete analysis of GSM stock.

This week, Gold Fields (NYSE:GFI) drops from a C to a D rating. Gold Fields is engaged in the mining, exploration, extraction, processing, and smelting of gold. For more information, get Portfolio Grader’s complete analysis of GFI stock.

MAG Silver (AMEX:MVG) is having a tough week. The company’s rating falls from a C to a D rating. MAG Silver acquires and explores mineral properties with a focus on high-grade silver and gold. The stock also gets an F in Equity. For a full analysis of MVG stock, visit Portfolio Grader.

The rating of United States Antimony (AMEX:UAMY) slips from a C to a D. United States Antimony refines, produces, and sells antimony products such as antimony metal, antimony oxides, and sodium antimonate. The stock gets F’s in Earnings Momentum, Earnings Revisions, and Margin Growth. The stock currently has a trailing PE Ratio of 240. To get an in-depth look at UAMY, get Portfolio Grader’s complete analysis of UAMY stock.

Slipping from a D to an F rating, Midway Gold Corp. (AMEX:MDW) takes a hit this week. Midway Gold explores and develops mineral resource properties. The stock gets F’s in Equity and Cash Flow. The price of MDW has dropped 17.2% since last month. For more information, get Portfolio Grader’s complete analysis of MDW stock.

Louis Navellier’s proprietary Portfolio Grader stock ranking system assesses roughly 5,000 companies every week based on a number of fundamental and quantitative measures. Stocks are given a letter grade based on their results — with A being “strong buy,” and F being “strong sell.” Explore the tool here.