What can crystalize size tell us about where an igneous rock formed?

Crystalization is solidfying of atoms or molecules or things,,it can be speeded up depends on nature of something in terms of it's molecular force of attraction eg sand and loam soil also temperature and pressure above the sure to be crystalized

An igneus rock is formed where magma(molten rock) cool and solify(crystalized especially in volcanoes areas

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.