Grit Confusion

Please can someone help us - we are a little confused on this grit issue....
Is there such a thing as 'chick grit'?  We have 3 week-old Silkies and are concerned that the grit we were able to obtain might not be suitable.  It's 'Antwerp Natural Grit' and it has oystershell grit as well as 'silex stone' and 'red stone'.  The pieces of grit are from 1mm x 1mm up to about 6mm and although it says "for optimal digestion/provides trace elements" and has a picture of a pigeon on it (about the same size as our chicks), we would like to be sure it's o.k. as a previous answer to our query said; "be sure to provide chick grit" ...well, 'Cornwall Farmers' have never heard of chick grit (they sell this 'Antwerp Natural Grit')
Please can someone reassure us?  Thanks.