Help Received SN, but it feels hardened

[mapleboy]

I've finally received my SN! It's in a sealed envelope, and the substance inside is quite hardened. Is this normal for SN before you put it into water? Could anyone provide insight on this? It was a bit hot outside and I wasn't able to retrieve the package until about 2-3 hours after it was delivered, so I'm hoping it hasn't gone bad already...

Edit: Added a photo of the sealed envelope

 

[ForestGhost]

That's normal

 

[swankysoup]

Anyone know how long you can store a sealed package like that before SN goes bad, and what is the temperature range for storing? Some posts say it's really stable for years, others say something else.