A spelljamming mine is a one foot brass sphere. It weighs about fifty five pounds. It is just the right size to be fired from a heavy catapult.
The technological part of a spelljamming mine consists of its arming mechanism. A mine must be 'armed' in order to activate its magic. Arming is done by pressing a series of tiny studs on the outer surface of the mine. The studs need to be pressed in the correct order to activate the mine. The arming sequence is a code that is specific to each mine. The code is an 'anti-tamper' system that causes the mine to explode if the wrong arming sequence is entered three times in a row. The arming sequence is highly complex and even someone who knows the correct sequence can sometimes press the wrong studs while entering the code.
The magical part of a spelljamming mine consists of an enchantment that allows it to detect a spelljamming helm within one thousand feet. When the mine is armed, it will remain dormant for between two and sixteen minutes. After this time, the mine's spelljammer seeking ability will kick in.
Once armed and active, a spelljamming mine will remain motionless indefinitely, so long as no ship approaches within its one thousand foot range. If a ship does come within that distance the mine will move rapidly towards the ship. The mine travels at a speed of three thousand yards per minute and is highly effective at changing direction. If the mine hits the ship it is chasing, the charge contained within it will explode. If the mine flies through space for four minutes without reaching its target, the charge will also explode.
An exploding mine detonates with enough force to damage ships and injure crewmen in the area of the impact. It may also cause a fire. Like all explosive devices, a spelljamming mine will explode with three times as much force if encountered in the phlogiston.
The variable dormancy period and the unpredictable nature of spelljammer combat means that a spelljamming mine is a dangerous weapon to use in a ship-to-ship dogfight.
Nobody knows who invented spelljamming mines.
They are sometimes sold by the arcane, but only certain arcane appear to have access to these devices. Other arcane either do not have access to spelljamming mines or are unwilling to sell them.
Spelljamming mines have occasionally been offered on the open market by other sellers, but this carries the risk that the seller might not be aware of the correct arming code.
There are two theories surrounding the spelljamming mines.
Created by the arcane
Many people suspect the arcane created these techno-magical weapons.