Gems & minerals

Peridot is gem-quality olivine. Olivine is quite common but peridot is rare, so peridot is considered a precious gem.

Quartz is the second most common mineral on the surface of the Earth after feldspar. It is made of silicon dioxide in a crystalline structure. Quartz naturally forms colourless six-sided crystals, and is transparent or slightly translucent. Quartz that is milky or is coloured has impurities in it. Quartz that is a pretty colour is usually given a different name, like amethyst.

Rose quartz is simply quartz containing impurities that gives it a delicate pink colour. It is popular for jewellery, and for carving small ornaments and trinkets from.

Rust is what happens to iron when there is moisture around. Things will rust faster if there is any salt in the water, which happens often near the sea or if salt has been used to de-ice roads or href="/s/sidewalk">sidewalk.
Rust is a distinctive reddish-brown. It is common to see old cars falling apart from rust.

Sapphires are deep blue gemstone quality corundums. They are made from aluminium oxide crystals, the same as rubies, with the blue colour from traces of titanium and iron. Sapphires are very hard and have industrial uses as well as being used in jewelry.

Slate is a type of stone that has a clear grain to it and can be split into quite thin pieces. Slate shingles have been used for centuries to make rooves out of, and can also be used for tiling floors or building walls out of.

Sodalite is a blue stone that is found in large veins. It is one of the minerals found in lapis lazuli. Large quantities of sodalite are opaque but the individual small crystals are transparent.

Sunstone is a type of feldspar (a common silicate rock) that has a crystalline structure that reflects the light in a very attractive, spangled way. It is a popular gemstone because of this sparkle.

Tanzanite is a mineral that looks a different colour depending on what angle you look at it from - it can be sapphire blue, violet, or burgundy. Tanzanite is a rare gem, found mostly in the foothills of Mount Kilimanjaro.

Pure topaz is made from crystalline silicate of aluminium and fluorine. When it is pure it has no colour, but can be coloured pale yellow, brown, pale green, reddish or even rare instances blue if the stone contains impurities.
Topaz has been used in jewellery for thousands of years, and originally any clear yellow stone was called topaz. Now only stones that are the correct chemical composition can be called topaz.