I had this happen on another female same size about six months ago. I watched her five birth to what I thought was a huge pile of cuttlebone. Smae material as this, 2x the size.
I believe hard urates appear when the tort has been or is dehydrated. I also think they can appear if the tort is getting excessively high amounts of proteins. I would give daily soaks and make sure that water is always available in the enclosure. If this is a tort that you have had for some time and know that it should be hydrated then I would evaluate the diet
First, these urates, and stones have all been shown to be purine based and no calcium based stones have been found in tortoises in all the actual studies of sample I have found. That means it is more of a protein problem and not calcium related.
I also have seen this type of excretion by tortoises I have and cannot exactly link it to just hydration as there was no change in their husbandry yet, a few did put out more grainy urates. My best guess currently is that diet is a key. An eater who finds/picks out more protein in the food available? And it does seem the more high fiber available, the less I see this. The last I saw it with my sulcatas was early spring before I had a new bale of hay in their enclosure and lots of new clover growth in the enclosure. So, maybe good high fiber with good gut movement helps in them also releasing urates more frequently before it starts to precipitate into harder urates??
The availability of water should make a difference. Since the longer they hold water instead of flushing and replenishing, the more the concentration of uric acid builds and can then precipitate into the beginning of stones. When a tortoise find a good water source ever notice how it with drink copiously and also release a great amount of water? They do this in the bath too if you notice, but sometimes hard to see as they are immersed in water. This is their way of keeping uric acid concentrations low in their bodies. So perhaps a tortoise can also simply choose not to 'refresh' their water held and will be more prone to a harder urate build-up?? If so baths may be a help. My tortoises are quite large and not forced bathed very frequently at all any more. So their choice becomes a factor with them.