How to handle Derived Classes with overridden Generic Types in Lists?

I want to create a resource manager with customly typed derived resource classes like Texture1D, Texture2D, etc. Therefore I would like to override a generic type from the parent, so I`m able to return the resource data without casting it from object. (Also structs are possible with this solution).

See this approach if the text above was a little bit unclear:

I create an interface IResource. (1)
Then an abstract class implementing this interface. (2)
And finally my custom resource, which derives from Resource<T>. (3)

//1
public interface IResource : IDisposable

//2
// This class returns Data as T
public abstract class Resource<T> : IResource 

//3
// This class returns Data as GLEXTexture2D
public class Texture2DResource : Resource<GLEXTexture2D>

Basically, I have a ResourceManager with a List of IResource's which can add resources like this:

Texture2DResource resource = new Texture2DResource("a path", ResouceThreadAccess.LOCAL);
resourceManager.RegisterResource(resource);

Is this an acceptable design decision? In my oppinion the generic overriding code looks a bit confusing when creating new resources. Is there a better way to solve this tripple inheritance?