Much of our focus when we think about jewellery is on precious gemstones but less valuable gemstones can be used to make beautiful jewellery as well. I particularly like jewellery made of hardstones from the quartz family, particularly agates, jaspers, and chrysophase.

Quartz contains a range of different categories of gemstone, with a large range of stones described as microcrystalline (also called cryptocrystalline). This category of quartz contains varieties of chalcedony gemstones, such as agates. Strictly speaking, an agate is known for its concentric banding. However, there are some agates that don’t display banding. Instead, they contain inclusions that create beautiful patterns. The most common one is a moss agate. The stone can have a clear to milky white body, with dentritic inclusions of oxides of manganese or iron. Dentrite means tree-like (from Greek) and the inclusions form patterns that look like moss, lichen or branches. The inclusions are coloured green, brown and red.

Moss agate stone (part of antique bracelet)

There are a number of different types of similar agates to moss agate. One is dentritic agate (also called mocha stone as it was first found in Mocha, Saudi Arabia) which also has a colourless to translucent background and inclusions in brown or black. The Maltese cross pendant below is a good example.

Antique dendritic agate Maltese Cross

Another type of agate is a landscape or scenic agate where the inclusions resemble a landscape. The Georgian swivel ring has an agate often called mosquito agate as it looks as if it might have small insects in it.

Georgian swivel ring

Generally, though, we call agates with dendritic inclusions moss agates.