y capital and operating costs of a development project; y environmental considerations and permitting; y adequate access to the site, including competing land uses (such as agriculture); y applicable tax rates; y foreign currency fluctuation and inflation rates; and y availability of financing. y declines in the market price of the various metals we mine; y increased production or capital costs; y reduction in the grade or tonnage of the deposit; y increase in the dilution of the ore; and y reduced recovery rates. y delays in new project development; y net losses; y reduced cash flow; y reductions in reserves; y write-downs of asset values; and y mine closure. Our ore reserve estimates may be imprecise. Efforts to expand the finite lives of our mines may not be successful or could result in significant demands on our liquidity, which could hinder  our growth and decrease the value of our stock. Our joint development and operating arrangements may not be successful. 8 [ HL:10-K ]  We have in the past entered into, and may in the future enter into joint venture arrangements in order to share the risks and costs of developing and  operating properties. In a typical joint venture arrangement, the partners own proportionate shares of the assets, are entitled to indemnification from  each other and are only responsible for any future liabilities in proportion to their interest in the joint venture. If a party fails to perform its obligations  under a joint venture agreement, we could incur liabilities and losses in excess of our pro-rata share of the joint venture. We make investments in  exploration and development projects that may have to be written off in the event we do not proceed to a commercially viable mining operation. See  Note 16  of  Notes to Consolidated Financial Statements . The #4 Shaft project, an internal shaft at the Lucky Friday mine, is expected, upon its completion, to provide deeper access in order to increase the  mine’s production and operational life. We commenced engineering and construction activities on #4 Shaft in late 2008, and our Board of Directors  gave its final approval of the project in August 2011. Work on the project thus far has included: detailed shaft design, excavation of the hoist room and  off shaft development access to shaft facilities, hoist installation, placement and receipt of orders for major equipment purchases, 367 feet of vertical  shaft excavation, and other construction activities. The #4 Shaft project, as currently designed, is expected to involve development down to the 8800  foot level and capital expenditures of approximately $200 million, which includes approximately $92 million that has been spent on the project as of  December 31, 2012. At the end of 2011, MSHA began a special impact inspection at the Lucky Friday mine, and as a result MSHA ordered the Silver  Shaft to be closed until we removed built-up cementitious material from the shaft. The Silver Shaft is the primary access way from the surface at the  Lucky Friday, and the order resulted in a temporary suspension of most operations at the Lucky Friday, including work on #4 Shaft. Access to the #4  Shaft project was restored in the first quarter of 2013, and we believe that our current capital resources will allow us to proceed. However, there are a  number of factors that could affect completion of the project as currently designed, including: (i) a significant decline in metals prices, (ii) a reduction in  available cash or credit, whether arising from decreased cash flow or other uses of available cash, (iii) increased regulatory burdens, or (iv) a significant  increase in operating or capital costs. One or more of these factors could potentially require us to suspend the project, defer some of the planned  development, or access additional capital through debt financing, the sale of securities, or other external sources. This additional financing could be  costly or unavailable. One of the risks we face is that mines are depleting assets. Thus, we must continually replace depleted ore reserves by locating and developing  additional ore. Our ability to expand or replace ore reserves primarily depends on the success of our exploration programs. Mineral exploration,  particularly for silver and gold, is highly speculative and expensive. It involves many risks and is often non-productive. Even if we believe we have found  a valuable mineral deposit, it may be several years before production from that deposit is possible. During that time, it may become no longer feasible  to produce those minerals for economic, regulatory, political or other reasons. As a result of high costs and other uncertainties, we may not be able to  expand or replace our existing ore reserves as they are depleted, which would adversely affect our business and financial position in the future. These estimates are based on geological and other interpretive data, which may be imprecise. As a result, actual operating and capital costs and  returns from a development project may differ substantially from our estimates, and, as such, it may not be economically feasible to continue with a  development project. Our ore reserve figures and costs are primarily estimates and are not guarantees that we will recover the indicated quantities of these metals. You  are strongly cautioned not to place undue reliance on estimates of reserves. Reserves are estimates made by our professional technical personnel, and  no assurance can be given that the estimated amount of metal or the indicated level of recovery of these metals will be realized. Reserve estimation is  an interpretive process based upon available data and various assumptions. Our reserve estimates may change based on actual production  experience. Further, reserves are valued based on estimates of costs and metals prices, which may not be consistent among our properties. The  economic value of ore reserves may be adversely affected by: Short-term operating factors relating to our ore reserves, such as the need to sequentially develop ore bodies and the processing of new or different  ore grades, may adversely affect our cash flow. If the prices of metals that we produce decline substantially below the levels used to calculate reserves  for an extended period, we could experience: