The phrase "a small slab" is correct and usable in written English.
It can be used to describe a piece of material, typically flat and rectangular, that is small in size.
Example: "The artist used a small slab of marble to create a delicate sculpture."
Alternatives: "a tiny piece" or "a little panel".
I pulled off a small slab to see what might be hiding under it".
Most memorable was a small slab of fatback from an Iberian pig, served with almond milk, in a brilliant marriage of richnesses.
Found built into south wall of pit a small slab stela [26-4-206, inscribed for Mestju, his wife Nebuhetep and daughter Khenut also shown], broken in two by pressure of wall above.
Likewise, a Cantonese throwback called duck pancake -- a small slab of crisp, rich duck on a pillow of plain white bread that absorbs its plum-scented juices -- is surprisingly satisfying.
His homage to Wiener schnitzel is a tender veal cutlet fried and served with hammered pea pods, lemon segments and capers and topped with a small slab of pickled herring: this is to remind you that you are not in Munich.
Rarely, perhaps never, has so spectacular a web of myth been woven around so unprepossessing an object: a small slab of limestone that lurks behind a metal grille set into a derelict, partially burnt-out building on Cannon Street in the City of London, with only balled-up pieces of chewing gum and dust for company.
A smaller slab protruding from a side wall provided a desk.
The thin, small slab has a touch-screen which displays whatever buttons, keys or icons are relevant to the task in hand.
A small stone slab cantilevered from the wall serves as a bench.
A punch is a precise sculpture — a three-dimensional letter form in reverse — that is struck into a small copper slab known as a matrix to create a mold.
