WA Mines and Petroleum Minister Bill Marmion announced this morning that the value of the state's mineral and petroleum industry last year reached $114 billion, eclipsing 2013 by $200 million.

Together, iron ore and gold accounted for $73.7 billion (85%) of mineral sales.

The petroleum sector's growth revealed where the investment pendulum swung last year, albeit much of that investment was planned before prices started falling mid-year.

Though iron ore accounted for $65 billion (75%) of mineral sector sales, that was down $3 billion from 2013.

"WA's leading position is backed by the certainty and stable investment environment resulting from the state government's long-running regulatory improvement program," Marmion said.

"We've removed barriers to investment and prioritised safety, environmental and approvals reforms."

This investment figure was one of the key mining and petroleum industry statistics released by the Department of Mines and Petroleum, ahead of publication of next month's annual statistics digest.

Although recent falls in commodity prices have caused some companies to re-evaluate their investment position, the resources sector is set to continue playing a dominant role in the WA economy, with planned or potential WA resources projects valued at $118 billon.

This month, WA had an estimated $179 billion in mining and petroleum resource projects under construction or committed.

"There are a number of projects, particularly in iron ore and LNG that are currently being developed or expanded," Marmion said.