wirefury on "Using Custom Taxonomies As A Class Selector"

<li class="col-md-2 panel panel-default mix beige granite" data-name="Picasso"><img src="<?php bloginfo('url'); ?>/wp-content/uploads/granite/Picasso.jpg" class="img-responsive"><p>Picasso</p></li>
        <li class="col-md-2 panel panel-default mix black granite" data-name="Earth Glitter"><img src="<?php bloginfo('url'); ?>/wp-content/uploads/granite/EarthGlitter.jpg" class="img-responsive"><p>Earth Glitter</p></li>
        <li class="col-md-2 panel panel-default mix black granite" data-name="Blue Sapphire"><img src="<?php bloginfo('url'); ?>/wp-content/uploads/newslabs/granite/BlueSapphire.jpg" class="img-responsive"><p>Blue Sapphire</p></li>

My goal is to use the custom post types and their respective custom taxonomies I've created in a loop.
For example:
Color:
Brown
Yellow
Gold
Green

Stone Type:
Marble
Granite

Here's the loop I wrote:

<ul id="Grid" class="just grid">
<?php
query_posts( 'post_type=material');
if (have_posts()) :
	while (have_posts()) : the_post();
?>

	<li class="col-md-2 panel panel-default <?php wp_get_post_terms($post->ID, 'color', array("fields" => "all")); ?> mix" data-name="<?php the_title();?>"></li><img src="<?php wp_get_attachment_image_url('$id'); ?>" class="img-responsive"><p><?php the_title();?></p></li>
<li class="gap"></li>
<?php endwhile;?>

</ul>
<?php else:?>
<h2 class="center">Not Found</h2>
<p class="center"><?php _e("Sorry, but you are looking for something that isn't here."); ?></p>
<?php endif; ?>

My issue is that I can not seem to get the custom taxonomies of each custom post to get added into the class of the

I've also gone down the post_class by adding the taxonomies to the available post classes but that gave me more classes than I needed and broke the loop.

Thanks in advance for anyone who can help or even point me in the right direction.

WP4LYFE!!! Amiright?