The Mercurial Eye, powered by a Klein Star, turns raw EMC into your choice of block and places nicely stacked walls of the target block or smooth walls. If you choose, the Mercurial Eye can transmute the target block into a block of your choice using the existing block's EMC to defray the cost of replacing.


Crafting GUI.png


Brick (Block)

Brick (Block)

Brick (Block)

Red Matter



Brick (Block)

Brick (Block)

Mercurial Eye

Raw Materials Needed
28 Diamond Diamond
2 Grid Obsidian Obsidian
20 Grid Clay Clay balls
1920 Grid Coal Coal


2012-10-27 15.38.25
The Mercurial Eye has the power to build walls straight from the energy source of a Klein Star. To change the area covered by the Eye, press the Charge Key (V). To open its GUI, press the Extra Key (C). To change mode press the Toggle Key (G).

To uncharge the eye and make the area smaller you must sneak/crouch (shift key) and press the Charge Key (V).

Eyes are attached to their users - if you lose or destroy one with a Star or targeted block still within, the internal inventory will persist until you get a second one.

Upon opening, you will see a target slot, used to select the block of choice, and a Klein Star slot, which you are required to give a source of power. It's possible to place non-block place-able items in the Target slot, such as Ladders or torches, but the item will not be placed correctly, and will drop once the block is updated. The Mercurial Eye has 4 modes:

  • Creation Mode - This mode acts as if you were holding the target block; useful for precision work. Be careful - the Eye does not care for your location when placing the block down.
  • Extension Mode - The wall you are building extends from existing structures. This is extremely useful for things such as aiming down and creating bridges. Your position relative to the aimed face determines how the extension is oriented. Requires charge, which lays down blocks in a square around the aimed block.
  • Pillar-Extension Mode - This mode creates a huge pillar which extends in the opposite direction of the aimed face, i.e. away from you. Requires charge. Do not fire upwards. At full charge it creates a 3x3x15 pillar in the direction you are aiming.
  • Transmutation Mode - Whatever your target block is, it will transmute the blocks you target to, similar to extension mode. If the EMC of the changed block was greater than your target, you absorb the EMC. If it was less, you spend EMC. If it is the same, the power costs nothing! This function can be very helpful for building in a material that is particularly difficult to remove, such as obsidian. Rather than building with obsidian, simply build in dirt or another easily cleaned up block, then convert it into obsidian when the structure is done. At full charge it transmutates a 9x9x1 area.


  • When placing an item (such as a door or lava/water bucket) in the "block" section of the Mercurial Eye and attempt to place it, the world will crash. However, you are still able to load the world. (SSP Tested)
  • In SMP, using pillar mode with max charge might crash your client, will not break world save, however.
  • It is possible to place the Mercurial Eye into it's own Klein Star slot. If you then close the GUI it will dissapear from your inventory until you create another Mercurial Eye to recover it.
  • When placing Redstone Dust using a Mercurial Eye in SMP it seems to cause an Internal Server Error (This needs testing)
  • Most blocks with EMC value should be useable with the Mercurial Eye; however there are a few block types such as Wooden Planks (specifically, data 5:1 EMC value 8) and Coal Ore that cannot be transmuted into something else using the Mercurial Eye. 
  • You can't stack slabs on top of each other, as it counts as another block.

Start a Discussion Discussions about Mercurial Eye

  • EMC farm

    2 messages
    • If you can charge the klein star by transmuting to a smaller value, then whic transformations will fully charge each klein star?
    • There is no transformation that will fully charge any klein star perfectly without burning up extra EMC or not filling it fully.
  • Mercurial Eye

    2 messages
    • What key do you press to change modes? I know V & shift V change the strength and C opens the GUI, but how do you change the mode?
    • you press G, but if your controls are messed up press "Esc" and click on Controls, then scroll to the bottom and look look at the top...

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