Combat (laser) crystals and mining crystals in EVE Online may receive "damage" and eventually be consumed (or in common terms, shatter). These crystals have a Hit Point value much like any other destructible object, and shattering occurs when enough damage is taken by the crystal to lower its hit points to zero. The life expectancy of a given crystal, i.e. the average amount of time it may be used before it shatters, may be calculated from its attributes.
As with most transportable objects in EVE Online, one may right-click a combat or mining crystal and choose Show Info. The information in which we are interested are within the Attributes tab of the Show Info window.
There are four different attributes that affect the life expectancy of a crystal. These attributes function identically for both combat and mining crystals.
This is the total Hit Points of the crystal. Currently, all crystals in the game have exactly 1 HP.
This attribute is the chance of the crystal taking damage upon every activation cycle. For example, a Volatility of 10% would mean that each activation cycle the crystal has a 10% (1 in 10) chance of receiving damage. The actual amount of damage is fixed, and is given by the Volatility Damage attribute.
Some combat crystals have a 100% chance of damage per shot. It also means that the life expectancy of these combat crystals may be calculated exactly, because every shot will always damage the crystal. (Currently, all faction combat crystals have a 100% Volatility, i.e. a 100% chance of crystal damage inflicted per shot.)
In terms of Volatility, an Activation Cycle is a single cycled use of a laser crystal by the turret within which it is loaded. With combat crystals, each time the energy weapon is fired is considered one cycle.
With mining crystals, a cycle may begin with the activation of the mining laser and may end with either the deactivation of the laser or the acquisition of materials (ore or ice). This means that a cycle is completed even if a mining laser is turned off early. Repeatedly turning a mining laser on and off will risk damaging the crystal whether or not any actual materials were mined.
This is the actual amount of damage the crystal may receive during an activation cycle based upon its Volatility.
Crystals Take Damage
This attribute is always either True or False. If it is True, then the crystal actually takes damage based upon the other attributes above, and it will eventually shatter.
Currently, the only crystals in the game whose Crystals Take Damage value is False are the Tech-1 combat crystals. These will never take damage and thus they may be used indefinitely. Note that if the value of this attribute is False, then it will not even be listed in the Attributes tab of the Show Info window.
The formula for determining average life expectancy of a crystal is simple:
Life Expectancy (in cycles) = Structure Hitpoints / Volatility / Volatility Damage
One may then multiply the expected cycles by the cycle time to calculate a crystal's life expectancy over time. Remember that Volatility is a percentage, so for example, a crystal with a Volatility of 10% must use the value 0.10 in the equation.
The Plagioclase Mining Crystal I has a Volatility of 10%, which means that for every cycle there is a 10% chance that it will receive damage. The amount of damage it receives will be the Volatility Damage value of 0.025 HP. It will shatter when its total damage reaches the Structure Hitpoints value of 1 HP.
This means that, on the average, the crystal has a life expectancy of 1 / 0.10 / 0.025 = 400 cycles. With a standard (unbonused) strip mining cycle time of 180 seconds, one may estimate that a crystal will endure approximately 72,000 seconds, or 20 hours, of constant mining before shattering.
Tech 2 crystals will last, on average, 200 cycles or 10 hours of constant mining with the standard cycle time of 180 seconds. Note that bonuses from an Orca or Rorqual (which can reduces cycle time by up to ~33%) will cut this life span to 7.5 hours.