The phrase "a gigantic chunk" is correct and usable in written English.
It can be used to describe a large piece or portion of something, often in a figurative sense.
Example: "After the storm, we found a gigantic chunk of the tree had fallen in our backyard."
Alternatives: "a massive piece" or "a huge portion".
Meanwhile, the Rock itself is a huge, gigantic chunk of limestone — almost 1,400 feet tall — that is essentially an immense fortress.
Their rent has recently shot up, from £1,100 to £1,500 a month, and I am horrified by the gigantic chunk it takes out of her income.
There is now no way, with hindsight, of clawing back the lost public benefit from this gigantic chunk of real-estate speculation.
"We were all gathered around staring at this lake," the cinematographer Hoyte van Hoytema recalled, "and Chris took his shoes and socks off and just strode out into the water, going straight towards that gigantic chunk of ice.
The author of that remark, Rep. Paul Ryan (R-Wisconsin), said that he was awestruck after watching gigantic chunks of glacier disintegrate and crash to the sea.
Bamdad thinks her nanoparticle probes are ideally positioned to solve gigantic chunks of the problem because of their ability to yield information about how proteins bind together.
Where as the Moto RAZR's infamous microphone chunk is like a gigantic messed up chin on an otherwise lovely lady, the Flip 8220's hinge is like a massive, lop-sided arse that you just can't pull your eyes off of.
Like its northern neighbour, the population is younger than average and a large chunk of people are employed in the retail sector – thanks, in part, to a gigantic Amazon distribution centre just off the M1.
Unfortunately for me, regularly spending a chunk of the nighttime in a state of suspended consciousness and drool turns out to be a gigantic deal.
