Insulation Question?

I came across this substance today throughout the attic over a loose fill insulation. It was a light brown powder but almost seemed slightly compressed over existing loose fill and I haven’t ever come across it before. I came across phlogopite mica powder online which looks similar but wasn’t able to find much info beyond that.

From here it looks like cellulose over fiberglass.


I think it’s just cellulose on the top. I think it sometimes gets that “caked over” look when there was a shit ton of dust and it all settles.

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Thank you both, that would make sense, I think the cakes over look is what was throwing me.

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Cellulose atop rock 0r stone wool.
Cellulose looks degraded. Compacted/compressed with dark fine fibers. The typical lifespan is 20 to 30 years, with degradation beginning as early as 15 years after installation. Most cellulose insulation will begin to settle at some point during its lifetime. Unfortunately, this settling creates aeration within the material that will cause the R-value to decrease by 15-20%. And if the insulation becomes disrupted due to moisture, constructional damage, or pests, it’s likely to lose more R-value.
Cellulose atop rock/stone wool or Glass fiber batt.
Uneven blanket.
Loose fill Cellulose Appears settled and degraded.

It’s cellulose actually.