Extremely pottery fragments and samples related to them, which were blackened...

[Volcano1985]

Extremely pottery fragments and samples related to them, which were blackened because of much heat, vitrified, and which lost its form properties by sticking together obtained from the field

Can you check this ?

[Mister Micawber]

.
There is only so much that you should try to get into one sentence, Volcano.

Extremely small (?) pottery fragments and samples associated with them, obtained in the field. They are heat-blackened and vitrified, and they have lost their original (?) form in adhering to one another.
_________________
Native English teacher at Mister Micawber's