Goodfellow offers two distinct types of glass products: The first are generally silica-based, non-crystalline (amorphous) solids which exhibit a glass transition and are brittle and transparent. The properties of glass materials can be readily modified to alter their optical performance and other characteristics. This type is available through Goodfellow's Ceramic and Glass Division. Generally, these products are made to order for customers, so we do not list them in our catalogue. Please contact us with your requirements. The second type of glass product is commonly referred to as "metallic glasses" or "glassy metals". In contrast to crystalline metals and alloys with highly ordered atomic structures, these are non-crystalline (amorphous) metals or, more usually, alloys. Our website details those glassy metals which are available from stock; please contact us if you are unable to find the item you specifically require.