23. EXPLORATION EXPENDITURE (NON-CURRENT) 2011 2010 Exploration and evaluation costs carried forward in respect of mining areas of interest Pre-production areas At Cost 827,947  53,353,863  Accumulated impairment - - Net carrying amount 827,947  53,353,863  Movement in deferred exploration and evaluation expenditure At 1 July net of accumulated impairment 53,353,863  51,567,468  Additions 4,820,071  3,343,349  Disposals (refer to note 38) - (372,574) Transferred to mine capital development (refer to note 21) (2,396,011) (929,905) Transferred to development areas (refer to note 21) (53,798,510) -  Expenditure written off (1,151,466) (254,475) At 30 June net of accumulated impairment 827,947  53,353,863  24. TRADE AND OTHER PAYABLES (CURRENT) (a) Trade creditors are non-interest bearing and generally on 30 day terms. (b) Sundry creditors and accruals are non-interest bearing and generally on 30 day terms. Due to the short term nature of these payables, their carrying value approximates their fair value. The ultimate recoupment of costs carried forward for exploration and evaluation phases is dependent on the successful  development and commercial exploitation or sale of the respective mining areas. Amortisation of the costs carried forward for the  development phase is not recognised pending the commencement of production. During the year exploration and evaluation expenditure of $53,798,510 relating to the Wingellina Nickel Project was transferred to  Mine Properties and Development. Completion of the first phase feasibility study in 2008 and signing the heads of agreement with  Jinchuan during the year to advance the project.  During the year a review was undertaken of each area of interest to determine the appropriateness of continuing to carry forward  costs in relation to that area of interest. Exploration and evaluation expenditure of $1,189,720 (2010: $295,820) was written off to  the income statement, $38,253 (2010: $41,345) of this expense is attributable to exploration and evaluation expenditure written  off in relation to the Collingwood Tin Project (refer to note 11). The major expenditure written off in the current financial year relate  to the Agaton Phosphate Project ($580,524) and the Mt Bischoff Tin Project ($359,272). The major expenditure written off in the  previous financial year related to areas of interest within the Wingellina and Claude Hills Projects. Management decided to abandon  future exploration of these areas due to low potential from results returned in the areas. 94  NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS FOR THE YEAR ENDED 30 JUNE 2011 2011 2010 Trade creditors (a) 3,205,562  5,480,419  Sundry creditors and accruals (b) 2,473,991  4,467,272  5,679,553  9,947,691 