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”).

Horsehead Holding (NASDAQ:ZINC) ratings are on the decline this week as the company earns a F (“strong sell”). Last week, it received a D (“sell”). Horsehead Holding produces specialty zinc and zinc-based products. In Portfolio Grader’s specific subcategories of Earnings Growth, Earnings Revisions, Earnings Surprise, Cash Flow, and Margin Growth, ZINC also gets F’s. The trailing PE Ratio for the stock is 908.00. Shares of the company have declined 2.9% over the past month. For more information, get Portfolio Grader’s complete analysis of ZINC stock.

Freeport-McMoRan Copper & Gold (NYSE:FCX) gets weaker ratings this week as last week’s D drops to a F. Freeport-McMoRan Copper & Gold is a copper, gold, and molybdenum mining company. The stock also rates an F in Sales Growth. Over the last month, the price of FCX has fallen 1.3%. For a full analysis of FCX stock, visit Portfolio Grader.

Hecla Mining (NYSE:HL) is having a tough week. The company’s rating falls from a D to a F rating. Hecla Mining explores, develops, and mines precious metals, gold, and silver. The stock receives F’s in Earnings Growth, Earnings Momentum, and Earnings Revisions. Earnings Surprise and Sales Growth also get F’s. The stock price has declined 1.2% from a month ago. For more information, get Portfolio Grader’s complete analysis of HL stock.

Randgold Resources (NASDAQ:GOLD) is on the decline this week, earning a D (“sell”) after receiving a C (“hold”) last week. Randgold Resources explores for and mines gold in West and Central Africa. The stock also gets an F in Earnings Momentum. The stock price has fallen 4.1% over the past month, equal to the 4.1% decrease the Nasdaq has seen over the same period of time. The stock has a trailing PE Ratio of 25.40. For a full analysis of GOLD stock, visit Portfolio Grader.

The rating of Pan American Silver (NASDAQ:PAAS) slips from a D to a F. Pan American Silver is a silver mining company with its principal property in Peru. The stock gets F’s in Earnings Momentum, Earnings Revisions, and Earnings Surprise. The price of PAAS has declined 0.7% over the last month. To get an in-depth look at PAAS, get Portfolio Grader’s complete analysis of PAAS stock.

This week, Vista Gold (AMEX:VGZ) drops from a C to a D rating. Vista Gold is engaged in the evaluation, acquisition, exploration and advancement of gold exploration and potential development projects. The stock gets F’s in Earnings Growth, Earnings Momentum, and Earnings Revisions. Equity and Cash Flow also get F’s. Over the last month, shares of VGZ have dropped 8%. For a full analysis of VGZ stock, visit Portfolio Grader.

This is a rough week for Nevsun Resources (AMEX:NSU). The company’s rating falls to D from the previous week’s C. Nevsun Resources is a gold producer and base metal developer. The stock also gets an F in Earnings Momentum. For more information, get Portfolio Grader’s complete analysis of NSU stock.

Silvercorp Metals (NYSE:SVM) earns a F this week, falling from last week’s grade of D. Silvercorp Metals is involved with the acquisition, exploration and development of silver-related mineral properties in China. The stock receives F’s in Earnings Growth, Earnings Revisions, Earnings Surprise, and Sales Growth. Share prices fell 9.3% over the past month. To get an in-depth look at SVM, get Portfolio Grader’s complete analysis of SVM stock.

Rio Tinto (NYSE:RIO) experiences a ratings drop this week, going from last week’s D to a F. Rio Tinto is an international mining group whose business is finding, mining and processing mineral resources. The stock gets F’s in Earnings Growth and Margin Growth. For a full analysis of RIO stock, visit Portfolio Grader.

The rating of Southern Copper (NYSE:SCCO) declines this week from a C to a D. Southern Copper is an integrated copper producer. The stock also gets an F in Sales Growth. Shares of the stock have been changing hands at an unusually rapid pace, three times the rate of the week prior. To get an in-depth look at SCCO, get Portfolio Grader’s complete analysis of SCCO stock.

Slipping from a D to a F rating, Schnitzer Steel Industries (NASDAQ:SCHN) takes a hit this week. Schnitzer Steel Industries is a recycler of ferrous and nonferrous scrap metal, a recycler of used and salvaged vehicles and a manufacturer of finished steel products. In Earnings Growth, Earnings Momentum, Earnings Revisions, and Sales Growth the stock gets F’s. For more information, get Portfolio Grader’s complete analysis of SCHN stock.

Gerdau‘s (NYSE:GGB) rating weakens this week, dropping to a D versus last week’s C. Gerdau S. A. is a Brazilian corporation that produces crude steel and related products. The stock also gets an F in Earnings Revisions. Investors seem to agree with the downgrade and have pushed down the share price 8% over the past month. For a full analysis of GGB stock, visit Portfolio Grader.

This week, Golden Minerals‘s (AMEX:AUMN) rating worsens to a F from the company’s D rating a week ago. Golden Minerals is a mining company with a focus on exploration, development, providing mining services, and growth through strategic business transactions. The stock gets F’s in Earnings Revisions, Equity, and Cash Flow. Shares of AUMN have declined 13.8% from a month ago. For more information, get Portfolio Grader’s complete analysis of AUMN stock.

Revett Minerals (AMEX:RVM) earns a F this week, falling from last week’s grade of D. Revett Minerals is a Silver-Copper Producer that owns and operates the producing Troy Mine and the development stage Rock Creek, located in northwestern Montana in the United States. The stock gets F’s in Earnings Growth, Earnings Momentum, Earnings Revisions, and Sales Growth. To get an in-depth look at RVM, get Portfolio Grader’s complete analysis of RVM stock.

Taseko Mines‘s (AMEX:TGB) rating weakens this week, dropping to a F versus last week’s D. Taseko Mines explores for and mines copper and molybdenum. The stock gets F’s in Earnings Revisions, Earnings Surprise, and Cash Flow. The stock currently has a trailing PE Ratio of 31.70. The stock price has fallen 16.2% from a month prior. For a full analysis of TGB stock, visit Portfolio Grader.

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.