Gas and petroleum exploration company L&M Mining expects to launch its initial public offering to raise $23.2m this month. The plan is that the new company, floated on 20c shares, will be dual-listed on the New Zealand and Australian stock exchanges by the end of November. L&M is the largest and most aggressive of all the "junior" exploration companies in New Zealand, not only in oil and gas, but also in promoting the vast southern lignite resource as a potential petrochemical source. It has five permits covering Otago and Southland containing an estimated 2 billion tonnes of lignite, a separate venture from the proposed float. While juniors historically stake a prospect and undertake drilling to work up estimates of the target oil…