export sharepoint userlist using powershell

I'm trying to export a list of all our users, specifically the fields name, email and PictureURL'

The end goal is to get a list of email adresses for users that dont have a user image. So we can chase them up

But for now im just trying to iterate through userlist and return a list of results in .csv format

$siteUrl="http://sp2010/"
$web = Get-SPWeb $siteUrl
$site = $web.Site
$rootWeb = $site.RootWeb
$UserList = $rootWeb.Lists["User Information List"]
$groups = $site.RootWeb.sitegroups
$Output = foreach ($user in $UserList) {"User: " + $user.name} 
$rootWeb.Dispose()
$web.Dispose()
$site.Dispose()
$Output > "C:\MembersExport.csv"

my output file just has a single line that says 'User:'