Metal particles in corals sand / gravel

[Habib]

I just saw a picture of the amount of metal particles attracted by a magnet from just 2 cups of coral sand.

The pictures are made by Tanne Hoff from Holland.

It is on a Dutch forum and the direct link to the picture is:

http://www.tanu.nl/tmp/koraalzand1.jpg

There might have been also other metal particles not attracted by a magnet.

FWIW the few larger gravel like particles on the magnet were according to the author (Tanne , also RC member as Tanu) were attracted by the magnet.

To get an idea how small the amount of sand was see:

http://www.tanu.nl/tmp/koraalzand2.jpg



Might be intersting to see if such particles can be found more often or is just an incident.

Nevertheless Tanne advices to use a magnet as well besides just washing the sand before use.

[Randy Holmes-Farley]

Wow, that's surprising, and concerning. You think it comes from metal equipment used in grinding? Not a good prospect, IMO.

FWIW, I have seen metal particles in silica sand:

"Take a close look at some commercial “silica� sand. It isn’t even close to being white, which an absolutely pure quartz sand will be. There are all sorts of different colored particulates in it (some are even magnetic and can be picked out with a magnet). "

from

Silica in a Reef Tank
http://advancedaquarist.com/issues/jan2003/feature.htm

[Habib]

You think it comes from metal equipment used in grinding?

I don't think that they grind it.

I suspect that the metal particles might have been from transporting and filling lines. Sieves might also be a possibility.


FWIW it is easy to imagine that parts of filling machines might corrode easily in the area in which they use it and with the type of product.

EDIT: Also the truck in which it is transported to the filling facility might release metal particles on the sides.

[Bomber]

It also depends on if it's land based or sea based.

[Tanu]

This is real coral sand, not broken coral or limestone. It is the same kind of sand as I've seen on a Balinese beach last summer.

I've used an old magnete cleaner to attract the metals.

Habib, thank you for bringing this topic here. I have to correct one thing. The ammount of metals on the first pic, is NOT removed from the ammount of sand on the second pic. The second pic was just taken to show the situation.

The ammount of metals comes from about 2-3 times the ammount of sand shown on the first pic. Even though, I think I did a strange discovery ;)