From ars technica -

Most plausible answer:

Activated carbon pellets, as a desiccant and to absorb any other airborne fumes from material outgassing, to prevent them from depositing on critical locations such as the media surface.

Most elegant answer:

It's a bit bucket. Those are all your erased bits.

_________________
An answer to a problem that is correct and efficient yet pleasing to behold is that problem's elegant solution.

Lost,

I was reviewing your post on hard drives.

The picture with the aluminum motor and silver connector.....are those pins silver?

The second picture with the rhodium......where is the rhodium?

It may need to take pictures of what I have and have you point it out to me.

Thanks for the help

Directly above the C in CPU

I don't recall this exact hard drive but the pins I've normally come across are nickel, silver, and gold plated nickel.

_________________
42 6F 61 72 64 73 6F 72 74 2E 63 6F 6D

Lost,

lol I'm a little slow.....
"Directly above the C in cpu"
I didn't understand what you were saying when I first read that...lol
I see that silver spec in the picture, my question is where is it at in the hard drive?
Would it be worth the time and effort to recover it from roughly 150 hard drives?

you can buy a testing solution for nickel, just look up nickle test kit on amazon.

you can also make the testing solution by dissolving a small bit of Dimethylglyoxime (aka: DMG) in a small amount of hydrochloric acid (aka: muriatic acid). EDIT! This is wrong!!! DMG is an indicator in ALKALINE solutions only! You need to dissolve it in sodium hydroxide (lye). A couple grams in a 50mL of NaOH will be plenty for a spot testing solution. Positive tests turn pink to bright red.

DMG can also be used to test solutions for palladium under the right circumstance EDIT: DMG is an indicator for palladium under acidic conditions... this was the source of my mix up!... its a rather handy chemical to have... and it smells like popcorn-butter! :p

a word of note about the DMG testing solution... it is very sensitive to nickle, but only tells you if that surface contains nickle. it does not necessarily mean it is all nickle, and there are many alloys out there with nickle in them.

edited a post above due to a mix up I realized today... sorry for screw up guys :(

It's a tiny dot on the paper to the right of purchasing and to the left of CPUs.

_________________
42 6F 61 72 64 73 6F 72 74 2E 63 6F 6D

Looks like we're all messing up today; lol.
They're attached to the read heads. And the rhodium is attached to that pieces.
Is it worth it? Well...!
I can dissect a modern drive in 30 to 45 seconds from whole to parts. That's from practice telling me where all the various screws are and what size. Habit more than anything. Whole you're looking at 50c-$1 and apart $3+ so there's value. If it's worth it to you.
If you're going as far as breaking down the drive snipping the ends of the read arms off is a 1 second thing.
Again they weigh nothing but add up quickly. I keep them in a plastic pill bottle. That extra moment to snip the heads off is worth it if you've gone that far.

_________________
42 6F 61 72 64 73 6F 72 74 2E 63 6F 6D

150 drives
Average 1 per minute to give you time to get the hang of it you're at 3 hours.
Ideally you'd or pulling around $3 per drive at the moment for $400. $133 per hour
iF you have yards that will buy every component and a refinery to buy the PM (gold pins, rhodium, nickel).
Just remember I'm including the controller board and a rhodium purchase in that. If the boards are missing you'll drop to less than half that payout very quickly.
And prices may vary depending on drive and location. Laptop drives are worth much less as scrap. Big massive full height drives are half again more and 5.25 inch drives can fetch over $10 as scrap or as little as $2.

_________________
42 6F 61 72 64 73 6F 72 74 2E 63 6F 6D