Tectosilicate Collection (page 3)

Banded iron formation
3, 000 million year old specimen of banded iron-rich chert from the Murchison Goldfield, Western Australia. The banding derives from differing amounts and oxidation state of the iron composite

Sandstone is formed by loose grains of quartz compacted and cemented together

Mesolite is comprised of (hydrated sodium calcium aluminum silicate). Its needle-like crystals formed inside a gas bubble in cooling volcanic rock

Quartz
A quartz specimen (silicon dioxide) from San Juan del Rey, Minas Gerias, Brazil

Quartzite

A large cut citrine
Citrine is the yellow and orange variety of quartz (silicon dioxide). Specimen held at the Natural History Museum, London

Citrine and sapphire
Fine and poor examples of gem cutting and polishing. A superbly cut citrine (a yellow variety of quartz) and a poorly cut sapphire (blue), a variety of the mineral Corundum (aluminium oxide)

A group of feldspar specimens
Amazonstone crystals and gems, pin set with sunstone, and moonstones. The feldpars are significant rock building minerals

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