Due to the modern chapter divisions, this verse has become disconnected from the situational context which caused the brother of Jared to approach the Lord with stones. In Ether 2:23, the Lord asked the brother of Jared what he thought should be done to light the vessels, since they could not have fire. The Lord did not provide the solution, but outlined the problem and allowed the brother of Jared to come up with a way to provide the light.
What the brother of Jared came up with was sixteen small stones that somehow had been “molten out of a rock.” The brother of Jared had created stones that would not have occurred in nature, and then asked God to further alter their nature. There are legends of miraculous lights associated with Noah’s ark, and perhaps that inspired the brother of Jared’s solution.