|Our 11" Suncatcher Talisman showing|
off a variety of crystalline solids, such
as a smoky quartz faceted crystal
A common place to find confusion is in the use of 'crystal' versus 'glass' in the materials listed for a handmade piece. To a geologist, these terms have a specific difference based on structure. To a bead artist, these terms are more likely to be differentiated based on chemical content. Let's talk about structure first ...
'Glass' is a solid substance where the structure of the atoms is irregular and amorphous (and which will turn into a liquid when enough heat is applied). There is no large scale order to be found in 'glass'. Conversely, the structure of a 'crystalline' solid is very regular. The internal matrix of a crystal is repetitive and highly ordered.
It is possible to have a 'glassy' form of a material that has the exact chemical composition as a 'crystalline' form. The most most well known crystal is quartz, made of silicon and oxygen, SiO2, in a nice repeating pattern. But SiO2 is also the major constituent of 90% of the glass in our everyday lives. A crystalline substance can be formed by cooling a liquid slowly, allowing the atoms to line up into a nice, repeating pattern as the stuff becomes solid. A glassy substance can be formed by cooling a liquid very quickly. The stuff becomes a solid before the atoms have time to line up.
This means that any 'crystal' in a necklace need only be made of a solid with a repeating structure to be referred to as 'crystal'. A designer that uses quartz crystal in a necklace will call it crystal, and be absolutely correct. Yet this can be misleading if you imagine all crystal means 'Swarovski.'
I'll post soon about crystal versus glass - composition!