Grindstone Pentahydrate
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Grindstone Pentahydrate is an upgrade material in Arknights.
Item description
An advanced grindstone used in the finish machining of weapon parts. Can be used for a variety of upgrades and the synthesis of D32 Steel.
Compared to normal Grindstone, this tool has an even more stable structure. It is highly non-reactive.
Usage
The second of the Grindstone-type upgrade materials, Grindstone Pentahydrate is similar but much more stable and non-reactive, thus making it more useful and essential for Operator skill Mastery training and the Elite 2 promotion of 5★ and 6★ Operators.
Due to its stability, the Grindstone Pentahydrate is an important material for the synthesis of D32 Steel.
Acquisition
Store
Grindstone Pentahydrates are available in:
- Distinctions Store (sometimes) for 10
. - Headhunting Parametric Model Store for 75
.
Special drops
| Operation | Sanity | Drop rate |
|---|---|---|
| 4-8 | 21 | Very Rare (~5%) |
| 7-17 | 21 | Very Rare (~5%) |
| 12-8 | 21 | Rare |
| 13-21 | 24 | Rare |
Workshop
| Product | Material(s) | LMD | Morale | Requires |
|---|---|---|---|---|
 1 |
 1  1  1 |
300 | 4 | Level 3 Workshop |
Trivia
- Pentahydrate is a suffix used for chemical compounds with five water molecules bound to it.
See also
- Grindstone – T3 counterpart