Special mahogany log

Special mahogany logs can be obtained by chopping down mahogany trees. They are obtained instead of the normal mahogany logs roughly 2.5% of the time, and yield the same amount of Woodcutting experience as normal mahogany logs when chopped. They cannot be obtained from Managing Miscellania. They cannot be lit for Firemaking experience. Juju woodcutting potions will send these logs directly to the bank. Sign of the porter will NOT send these logs to your bank, they get placed in inventory. Special mahogany logs have two uses, offered by both the Sawmill operator north-east of Varrock and the Plank maker in Taverley or Prifddinas in the Ithell district:
 * Sell them for each.
 * Exchange 2 of them for a completely free conversion of the logs in your inventory into planks. (In this case, assuming you use noted special mahogany logs and convert 27 mahogany logs for free, 1 special mahogany log is worth.

Special logs
The free conversion requires 2 of the same type of special log, which are also accepted by the sawmill as bank notes.

2 special mahogany logs can be used to convert up to 27 teak logs and/or mahogany logs into teak/mahogany planks saving you up to 40500 coins (27 mahogany logs at 1,500 coins each).

If you have 1 special or 1 of each, the sawmill owner will only offer to buy your special logs.

Drop rates
The estimated chance of cutting a special mahogany log is close to 2%. Being random it is possible to get several per load, or go many loads without any. It appears unlikely that woodcutting level or wearing a strung rabbit foot increases the chance of obtaining a special log, despite claims to the contrary. Using an inferno adze to collect special mahogany logs will decrease the overall yield of special mahogany logs, so a standard hatchet is recommended.

It has been noted by some players that it appears as though you are unable to obtain special logs while carrying a woodcutting urn in your inventory, but this is a myth, as it has been tested and special logs were received at roughly the same rate.

Financial considerations
A large part of the financial return on cutting mahogany comes through the conversion of a load of 27 mahogany logs to mahogany planks using 2 special log notes at the Sawmill operator. Mahogany planks are in high demand for the Construction skill.

With an estimated special mahogany log drop rate of 2%, out of every 100 logs you would have 2 special logs, which gives you 27 mahogany planks and 100-27-2=71 mahogany logs (if you convert 27 mahogany logs with the 2 special mahogany logs at the sawmill, losing the 2 special logs). The current Grand Exchange price for mahogany logs is coins and mahogany planks are  coins. Thus 100 mahogany logs (of which 2 are special) are worth 27 × + 71 ×  =  which is an average of  per log at current Grand Exchange prices. These rates are superior to cutting yew logs which take longer to cut and are sold for per log, albeit without the need for trips to the sawmill.

When cutting logs at the Hardwood grove and banking with Rionasta using trading sticks, each log takes 10 sticks to bank at a cost of 10 × =  per log. Further each entry to the Hardwood grove costs 100 trading sticks. By only carrying trading sticks and wielding a hatchet, 27 logs can be harvested per trip (without a Beast of Burden) at an additional cost of per log. Thus the total "tax" per log at current grand exchange rates for trading sticks is.

(Note: if you have completed Deadliest Catch, then there is a deposit box northwest of the general store that you can freely use, taking the parcel service out of the equation completely.)

At level 82 woodcutting at a fairly brisk rate of entering and exiting the grove and banking with Rionasta one can harvest and bank at least 410 mahogany logs/hr, and at level 93 at least 430/hr. At level 82, excluding time for sawmill trips, but subtracting out the banking and entry fees at market rates for Trading sticks, the return on mahogany log cutting in the Hardwood grove comes to per hour, and  at level 93. This is more profitable than cutting magic logs which produces approximately per hr at 93 woodcutting.

The occasional bird's nest would increase the hourly return. Higher woodcutting levels would increase the speed of harvesting and hence the hourly return. At a 2% special mahogany log drop rate, the expected return per log is coins, which can be multiplied by ones expected number of logs cut per hour to get an hourly return (excluding time for sawmill trips).

Sawmill trips for plank conversion do take some time, but are well worth the effort. By running 27 mahogany logs with 2 special notes from the east Varrock bank to the Sawmill operator for conversion, resting on the return trip with the musician (with ~50 Agility), it is easily possible to convert 1,053 mahogany logs to mahogany planks per hour, which is worth, as opposed to selling the logs on the Grand Exchange for , and the requisite 78 special logs to the sawmill operator for. A pack yak could nearly double this amount. Using lumber yard teleport scrolls makes this process the fastest, especially with a pack yak, though the cost per scroll can eat into profits. Teleporting to Castle Wars with a ring of duelling for banking and using the balloon transport system to travel to the sawmill is the second fastest (though it has a quest requirement), with the conversion of 1,500 or more planks per hour being achievable.

Alternatively doing this after a trip to the salt-water spa at Oo'glog will allow good number of full speed runs between Varrock east bank and the lumberyard. Using the Plank maker in Taverley will also speed up the process, as he is closer to a bank.

Trivia

 * In the hardwood grove in Tai Bwo Wannai, if you have at least one special mahogany log and no regular mahogany or teak logs, the game will think that you have no mahogany or teak logs and will therefore prompt you with a warning message.
 * Juju woodcutting potions will send these logs direct to the bank, furthermore, the Herblore Habitat itself is a very close teleport destination to two Mahogany trees within the northeast corner of the Kharazi Jungle - the closest Mahogany destination to a teleport location.
 * The sawmill wouldn't take special logs in noted form until an update on 14 January 2013.
 * When you acquire a special mahogany log while woodcutting, the game displays the message "You cut down a special mahogany log with an interesting grain pattern" as opposed to the regular "You get some mahogany logs."