Shares in AIM-list coking coal producer Beacon Hill Resources rocketed over 50% on Friday after the group received an "unsolicited, indicative, non-binding approach", valuing the company at over £140m.An unnamed third party has made an approach for the entire issued and to be issued share capital of Beacon Hill at a price of 16.25p per share in cash.The share price jumped to 13.12p by 13:08, 54.4% higher than Thursday's close of 8.50p. As of 13:08, Beacon Hill's market capitalisation stood at around £114.38m."The approach is at a very early stage and includes a number of conditions that may or may not be satisfied," the statement said.However, the firm said that the 16.25p-a-share approach - albeit at a 91% premium to the previous day's closing price - still undervalues the company. Despite the jump in the shares on Friday, the price is still significantly lower the 52-week high of 23.50p reached in January."Whilst the proposal is at a significant premium to the current share price, the board does not believe that, as currently drafted, the proposal fully reflects the value inherent in the group."BC