Jagex announced this on their homepage

"Today we have made an adjustment to rune essence mining due to players breaking rule 7 and rule 12, using macros to mine the rune essence and then sell it.
As you are probably aware we have various systems in place to detect people breaking rule 7 and ban them. These systems work very effectively at detecting people breaking this rule, and make macroing a really bad way to try and train a high level character.

The problem we are now solving is not a problem with our macro detection systems which are still working well, but rather a problem with banning being an ineffective punishment against abusers who only use very low level accounts, and who have no intention of ever playing the game properly.

Over the last few weeks we have banned literally hundreds of accounts a day for macroing at the rune essence mine. However the bans were ineffective as the abusers could just create more low level accounts that they didn't care about to mine more. We also track trades so we can ban the recipiant of the illegally obtained items, but the abusers in this case were swapping the runes for gp, and then selling the gp for real world money on auction sites. Of course the person buying the gp for real world money gets banned, because we track the money they received in an unbalanced trade to a macro account, but the seller doesn't care that their customers get banned shortly after, as they have their real world money by then.

The fundamental problem is that rune essence was one of the few areas of the game which could be used to generate a reasonable amount of RuneScape money on a 'throwaway' low level free account. Normally to earn large amounts of money quickly you need to level up an account first, and then of course you care if it gets banned so our normal deterrent is effective.

We have therefore split rune essence to have 2 grades. Normal essence can only be used to make the six basic runes, whereas pure essence can be used to make any rune. You can mine both types of essence at the same place as before. The kind of essence you receive is automatically decided when you mine the rock. You will always get pure essence only if your mining is over 30 and you are on a members' world, otherwise you will get normal essence.

As a one-off event whilst we introduce this, existing essence in your bank and inventory will have been automatically converted to pure essence if you are a member or have other members-only items in your bank, provided you have level 30 mining or runecrafting.

Since free players can only craft the six basic runes anyway, the normal essence is just as good for its intended purpose of letting free players do low level rune crafting. However it is not so useful for selling to members who want to make law and nature runes (who we believe buy the vast majority of rune essence in Runescape) which should reduce its price significantly and make it a much less appealing proposition for real world traders.

The only people who should be significantly affected by this are players mining very large amounts of essence on free accounts purely to sell to members. There are better way of making money on high level free accounts anyway, so this change should only really affect players trying to making large amounts of money on a low level free account - which is of course the exact idea.

We would also like to yet again remind our players NOT to break rule 12 and be tempted to buy RuneScape gold for real world money. Nearly all the gold being offered for sale in this way was generated by cheating on 'throwaway' accounts. If you buy it not only are you encouraging further cheating, but you run the very real risk of being banned yourself as the money you receive is dirty money and will be tracked. Again we have banned countless players for breaking rule 12 and fuelling this problem, and will continue to do so.

We hope most players will agree we shouldn't let rule breakers spoil this game, and we are determined to not let them do so. As well as banning, where necessary we will also make minimal changes to the game to make rule breaking unviable."

Now this update is completely unfair to paying customers(like me, vol341). The new essence is very hard to use, Pople cant make runes using the runecrafting skills anymore and Lots of people dont like it. Here you'll see it on the runescape forums = http://forum.runescape.com/lang/en/aff/runescape/forums.ws?27,28,245,22033714

they have made it to stop macroers, but this is not fair on the innocent players.

You will see lots of people don't like it. There are some great suggestions i have seen in there and they should be used instead of the update Jagex made.

So jagex, please change it back and use a different, more better suggestion from the Runescape forums. This will make us paying customers and free to play people too.

Thanks.