At a decrepit low-rise block of flats in South London British artist Roger Hiorns has turned what looks like an old squat into an unexpected crystal cave of wonder. Seizure is the latest commission from Artangel, in conjunction with Jerwood, which follows on their long tradition of transforming urban housing into large-scale immersive works of art.

Seizure is babyfaced Brummie Hiorns' most ambitious large-scale work to date. The 33 year-old artist from Birmingham made the work by pouring vast amounts of copper sulphate solution into a ground-floor flat, which then crystalised to create a profoundly ambiguous work.

On arriving at the brutalist concrete courtyard surrounded by boarded up flats, the setting for Seizure, we're provided with Wellington boots and gloves. It's a surreal experience walking into this shiny blue grotto, like taking a quick walk on the moon and then back to the grimy council estate.

During the creative process Hiorns wasn't entirely sure what, if anything, would be revealed and he admitted that this is a way of passing responsibility on and effectively taking himself out of the creative process.

The crystal growth is governed by a precise and yet uncontrolled logic and this ability to self-generate a sculptural form is why Hiorns chose to use it. Hiorns' use of copper sulphate as a transformative material in his work dates back several years. Other objects Hiorns has coated with the solution include BMW car engines, thistles and architectural models, all of which have emerged encrusted with a glittering layer of intense crystalline blue. Hiorns has also made sculpture with detergent, disinfectant, semen and fire. "I'm not somebody who's interested in a deliberate form, design or style. These materials - fire, foam or crystal growth - have their own behaviour and aesthetic, which takes me out of the equation."

These materials enable Hiorns to be physically, although not psychologically detached. In 2006 the first thing a depressed Hiorns wrote in his scetchbook for the New Year were the words ‘transgressive and vulgar' - this was the beginning of Seizure. "It's the enactment of a thought that came at a bad time. I always think of this piece as a deeply internalised project - an unrelenting, unknowing chemical activity going deeper inwards."

"It was never about beauty. That would just be banal. The work relates to a fear of losing control." But it is beautiful. The cobalt blue makeover is perfect and perverse, organic and systematic, showing the often difficult relationship between industrial, man-made and natural processes.

Hiorns' interest in Brutalist Architecture led him to covet a social housing block as his canvas. Initially he thought of the Robin Hood Estate designed by Alison and Peter Smithson in Poplar, East London - the first and most extreme block of its kind. "These kinds of buildings don't work - small pokey flats treading on individualist attitude. I have always been very distrustful of the collective, like my attitude to religion."

The block is set to be demolished after Seizure closes, so get down there.

Roger Hiorns SEIZURE open Tues-Sun until 2 November 2008 at 151-189 Harper Road, SE1. FREE.