Glittergreen cart

Images by Kbignell via Midjourney

Glittergreen carts are special carts designed to carry processed glittergreen from the Greenholt Mountain processing facilities to the far reaches of the continent of Halconiket.  Processed glittergreen is quite valuable and can be rendered useless by exposure to light, especially sun light.
To guard against the processed glittergreen being exposed to sunlight, the glittery powder is placed in heavy earthenware urns that are in turn placed in special carts with thick heavy walls and top that hold the urns securely inside in a heavily padded, dark material matrix.  Once the lid is closed securely, the urns barely move even if the cart is violently shaken.  The lid of the cart fits tightly and is secured and locked.  Each cart has its own set of guards on its trip in the small caravans that transport the glittergreen to its destination.  
The carts are made of a special magic resistant wood (arbalite) found only in the Greenholt mountains and are covered in black dragon leather hide.  Brass fittings complete the coverings.  The inside of each cart is a matrix of arbalite wood covered in soft black velvet padded with goose down.  Each square is a tight fit for the heavy earthenware urns that contain the processed glittergreen.
The packing and unpacking of these carts are done only inside the mine or the light proof receiving buildings at their destination.  Every effort is made for the entire shipment to not expose even the urns to any light source.
In addition to the security of the box on the cart, the suspension and wheels of the cart are unique.  The suspension consists of a double set of hung springs on magical gimbles.  The springs and gimbles keep the box of the cart from bouncing more than a minimum amount and keep the cart upright except for in the most extreme conditions.