how to add custom block before product tag on product view page in layout xml in magento?

i want to add my custom block before product tag or after product description on product view page in magento.

i used below code but it can't work

<catalog_product_view>
        <reference name="content">
            <block type="module/block" after="product.description" name="example_block"
            template="module/example.phtml"/>
            </reference>
</catalog_product_view>