Brown dust spots - Strange marks

[dukeyfilm]

Hi all, bit of a strange one . I have been having these small brown dust like deposits appearing over my sandstone patio 2 to 5mm in diameter)
Some pictures here:
http://s1052.photobucket.com/user....20spots
It is like some one has thrown small 'mud bombs' onto the patio. At first I thought it might be residue left from some 'red dust rain' that we sometimes get in the Uk but when I returned from work today there were some more, also on some of my patio furniture. I have compared it to the soil from my garden and it is more brown in colour than the soil.
Any ideas?
Animal droppings perhaps- birds?
Cheers
Mark

[seanandruby]

Do they appear more when it's windy?
Could be wind blown from roof, or as you say dropped by birds or summink.

[lemoncurd1702]

Look upwards; do you have an aerial/sat dish/basket ball net or summit that could drop rust.

[Tony McC]

It could be sediment from your roof tiles.

I have reddish concrete roof tiles that weather continually, leaving a browny-red sediment, not all that dissimilar to yours, in the gutters. If not regularly cleaned, a bit of grass or other vegetation will colonise the sediment in the gutter and then, when we get a dry spell (if we get a dry spell!) it tends to die off and birds will harvest it for a nest lining. As they grub it up, some of the sediment inevitably comes away with the roots and gets dropped onto my patio below.

Have a look at your roofing and your gutters.