I've seen quite a few silver blacks that dark - kept in a barn!
I believe that her sire is silver black... YOur mare appears to be a silver pinto, I think black.
The shades of the silvers are infinite - so many color changes thruout the year (s). I feel that age also plays a part, as well as drought or living conditions... My homozygous silver mares always "look" palomino during the winter - neither carries a cream gene.
This is the same mare - taken at different times of the year and different years! Pics taken oct 2009, Mar 2013 and May 2012. Currently she's not shed out and her shedded hair on my sweatshirt and jeans today - look white... haven't gotten to her undercoat or real summer coat yet. Because she's out on pasture, she fades quickly. She is heterozygous for black...
And when she was darkest! She's 20 yrs old in this pic taken May 2012...
I have a LOT of photos of her here:
Bell,
BellBitmarepair - these two mares are full sisters. Bit has the white face. Bell and Bit have both been bred to palomino and cremello stallions. Some of theri foals have been palomino and carry the silver gene, some have been silver buckskins. I don't have pics of most of Bit's foals... I only have a handful of Bell's... Bell had a silver buckskin colt at her side when I purchased her in 2009, her 2010 filly by a chestnut tobi is a silver tobi (GG) and her 2012 filly (classy) is a silver tobi. Kreture and GG have been tested, Classy mane hair is going in next week. I was hoping to have a foal out of Bell this year, but ... haven't. She stood for Iggy in October and again in Feb of 2013, soooo... we shall see.
You also state that you treated her for lice when you first got her. I found that the chemicals in some products affect both the mane and tail color(s) and the body of the silvers...
Stuffy coliced while pregnant in 2000. The family leasing her, after 4 days of pain meds but continued feeding (she still eats - especially if no longer painful!), brought her back to our vet clinic. It was touch and go for a week as she slipped in and out of septicemia ... Can't tell you how many times she was flushed or how many times she was given IV fluids over a 10 day period. Even w/ discounts, it was expensive and NCSU said that she'd probably never have made it thru surgery tho she DID make it thru the treatments she got at the vet clinic... She had a severe impaction. She slowly got better. She didn't lose the foal. Here are 3 pic of her with her foal - her mane has changed to red (it was more noticable later in the year - but these are only pics I have) EXCEPT for the pinto white part, her tail - the flaxen part had also changed to red and so did her forelock - but neither of those were as noticable:
https://lh4.googleusercontent.com/-JEuMMl184pE/TjtZyqqqmDI/AAAAAAAAHcQ/mJE7noF9Nl8/s461/StuffyColt20May01.jpg
http://i224.photobucket.com/albums/dd46/purplepaintpony/Stuffy%20-%20LP%20Painted%20Pufnstuff/Stuffy01ScoobeyB.jpg
http://i224.photobucket.com/albums/dd46/purplepaintpony/Stuffy%20-%20LP%20Painted%20Pufnstuff/Stuffy01ScoobeyA.jpg
I have 2 young mares that I would have sworn were silver BAYS, but I've now had them both tested.. They are both heterozygous black (Ee), no bay (aa) and one silver gene (nZ). Either of these two mares could produce chestnuts who could carry the silver gene. BUT bred to my current stallion - resulting foals would all be black based (could be hetero or homozygous black (Ee or EE) with no bay (he's EE, aa, nZ, TT), possible silver/possible homozygous silver, tobiano pintos (like your mare). If we retained the black and white colt we had this year (not sure that we would) - the black/white colt to these two silver black mares could produce a chestnut foal as the stallion is also Ee for black and if the resulting foal got an "e" from each, he would be chestnut... could still carry a silver gene - but you wouldn't see it.
Ami
Ami's sire is a black & white overo, her dam is solid. I thought her to be silver bay, but not sure now...
and
KoKo
I linked their names to their pages - you can see their pedigrees w/ pictures if I have them, and their color tests along w/ a photo album of that pony... I don't have a picture of KoKo's sire - but saw him in person in 2009. He was a dark silver with dapples and a very light flaxen mane and tail (liter than hers but not white)... I now have a picture of KoKo's dam in attached to her pedigree...
Our newest filly,
Bunny, is very, very lite in "silver" color and in the sun has already faded fast (she's not even a month old yet). I will be having her tested - to see if she is homozygous for silver.... she could be OR it could just be the shading in her foal coat.