Using XPath to select attributes with wildcards

I got HTML I need to parse, and I'm using C# and Html Agility Pack Library to do the selection of nodes. My html will look something like either:

<input data-translate-atrr-placeholder="FORGOT_PASSWORD.FORM.EMAIL">

or :

<h1 data-translate="FORGOT_PASSWORD.FORM.EMAIL"></h1>

where data-translate-attr-**** is the new pattern of attributes I need to find

I could use something like this :

//[contains(@??,'data-translate-attr')]

but unfortunately, that will only search for value INSIDE an attribute. How do I look for the attribute itself, with a wildcard?

Update : @Mathias Muller

HtmlAgilityPack.HtmlDocument htmlDoc    
// this is the old code (returns nodes)
var nodes = htmlDoc.DocumentNode.SelectNodes("//@data-translate");  
// these suggestions return no nodes using the same data
var nodes = htmlDoc.DocumentNode.SelectNodes("//@*[contains(name(),'data-translate')]");  
var nodes = htmlDoc.DocumentNode.SelectNodes("//@*[starts-with(name(),'data-translate')]");

Update 2

This appears to be an Html Agility Pack issue more than an XPath issue, I used chrome to test my XPath expressions and all of the following worked in chrome but not in Html Agility Pack :

//@*[contains(local-name(),'data-translate')]
//@*[starts-with(name(),'data-translate')]
//attribute::*[starts-with(local-name(.),'data-translate')]

My Solution

I ended up just doing things the old fashioned way...

var nodes = htmlDoc.DocumentNode.SelectNodes("//@*");

if (nodes != null) {
    foreach (HtmlNode node in nodes) {
        if (node.HasAttributes) {
            foreach (HtmlAttribute attr in node.Attributes) {
                if (attr.Name.StartsWith("data-translate")) {
                    // code in here to handle translation node
                }
            }
        }
    }
}