Pure essence can be used to create chaos, blood, death, soul, nature or cosmic runes
AND
Air, mind, fire, water, earth and body runes, which can be made using rune essence too.
Rune essence let's you craft all f2p runes but not member runes and pure essence let's you do every rune !
There is no best, all pure essence is the same from every mine.
You use rune essence/pure essence on a altar. (runecrafting)
Pure essence is mainly used in 'RuneCrafting'. You use it to create runes at one of the many rune alters.
To make 100k in Runescape mine around 1000 Pure Essence ( Members ) or around 3000 Rune Essence ( Non Members )
To get runes, you can either buy them from the various magic shops around Runescape, on the Grand Exchange, or make them from rune essence and pure essence at the runecrafting altars hidden around runescape. If you need help, my runescape username is Xeyran.
basicly normal essence makes onely normal runes but pure essence make combination runes learn about them here at this link http://runescape.salmoneus.net/runecrafting.html#combine
You can check by looking at your mining skill guide.
The question is quite unclear, but if you mean, what type of essence is used to craft law runes in Runescape, you use Pure Essence. Hope that answers your question.
Currently 110 coins each as of July 29, 2011.
Pure essence can only be mined by members, above a certain level. Pure essence can also only be used by members for runecrafting. Pure essence is required for the more advanced runes (the runes that can only be crafted by members). For the basic runes, you can use rune essence or pure essence, but pure essence is more expensive, and therefore a waste.
You could be looking at around 140k Per hour.
There is no such thing as "Icon Essence" in Runescape. There is, however, Rune Essence and Pure Essence. Rune Essence is acquired by, after completing the F2P quest: Rune Mysteries, teleporting to the Essence mines and mining with either less than 30 mining or mining in a F2P world. Rune Essence is used to Runecraft Air, Mind, Water, Earth, Fire and Body runes. Pure Essence is acquired by, after completing Rune Mysteries, teleporting to the Essence mines and mining with 30 Mining and up on a P2P world. Pure Essence is used to Runecraft all runes, including the ones Rune Essence is used to Runecraft.