Iron, zinc and coal miner China Natural Resources shed 20% of its value on the Nasdaq stock exchange in morning trade on Monday in the absence of any fresh news about its operations while China Shen Zou Mining lost over 8%, the worst performers in the sector. Investors are continuing to worry about the soundness of Chinese companies that came to the US market through so-called reverse listings with the value of the 98 companies declining sharply in recent weeks as creative accounting and other irregularities are uncovered at firms engaging in operations as diverse as software and timber.

Nasdaq reports farmers want so much fertilizer to meet demand for agricultural products that potash producers are raising their prices on an almost constant basis now. Back in January 2010, German potash producer K+S was charging 285 euros – roughly $407 – per ton of potash. As of now, bulk clients are buying potash at 363 euros or $520 per ton, a 27% net increase over the last 18 months.

A merger between Quebec-based ECU Silver Mining and Golden Minerals of Chicago announced on Friday had investors scrambling for the exits on Monday with the two companies at one point trading down 3.9% and 7% respectively on a generally bad day for silver stocks. The combined company worth over $600m with extensive assets in South America will keep its headquarters in Golden, Colorado and the Golden Minerals name and will be headed by Golden CEO, Jeffrey Clevenger.

Investment site Motley Fool says gold stocks such as Newmont, Goldcorp and Freeport-McMoRan are trading as though gold has lost its luster entirely and slipped back below $1,250 per ounce and that this latest bout of weakness in the gold mining shares – occurring when quality producers are awash in record cash flow and cozy profit margins – has yielded valuations remarkably depressed.

Viking Minerals commenced the review of pre-drilling and geological mapping of its South Dolly Varden gold / copper claims in Elko County, Nevada. This mapping is to facilitate a resolution of the zones of mineralization outlined by the surface geochem and rock samples and the 3,000 foot delineated coincident Induced Polarization (IP) anomaly with the intersection of the diamond drill core holes.

Lucara Diamond provided an update on the development of its 100% owned AK6 diamond project in Botswana. The AK6 mine, to be commissioned by year end, will ramp up to full production in early 2012 to deliver over 400,000 carats of high quality diamonds in its first year of operation. As at the end of May there were over 400 construction crew members on site and a total of 326,000 hours worked. With the overall project execution at 64% the project remains on target for process plant commissioning to commence in the Q4 of this year. Engineering is now 91% complete; procurement is at 81%; fabrication and delivery at 55%; and construction at 39% complete.

Bayfield Ventures announced a major gold and silver intercept on its 100% owned Burns Block property in the Rainy River District of north-western Ontario. The Burns Block is situated adjacent to the east and on strike to Rainy River Resources' multi-million ounce gold deposit.

Minera Andes announced drill assay results from the January – May 2011 drill program and a development update for the 100% owned Los Azules Copper Project, in San Juan Province, Argentina. Highlights from the recent drilling include a step-out drill hole, located approximately 250 meters west of the resource that returned 0.50% copper over 269 meters, including 0.95% copper over 45 meters. Infill drilling was generally in line with expectations, for example intersecting 0.66% copper over 395 meters and 0.63% copper over 237 meters.

Calibre Mining announced final assay results for the completed 9 hole, 2500 metre diamond drill program at its 100% owned Riscos de Oro gold-silver property in north east Nicaragua. The results are highlighted by hole RD11-016 that intersected 3.61g/t gold and 518.44g/t silver over 3.68 metres (14.41 g/t AuEq1,2) and hole RD11-017 that intersected 9.31 g/t gold and 336.06 g/t silver over 3.90 metres (16.31 g/t AuEq1,2). Read the full news release here. Photo is from Calibre Mining.