Year 8 Science
By Colin Price - High School Science Teacher
Year 8 Science
In Year 8 Science we study the rock cycle, and part of the rock cycle is the breaking down and weathering of rocks. When iron-rich rocks are chemically weathered due to acidic rainwater and atmospheric oxygen, the rocks are broken down into a mixture of clay and iron oxide, also known as ochre. Aboriginal people have been mining ochre for over 40,000 years and using it as pigments in ceremonies and cave paintings and as medicines.
The proportions of clay and the different iron oxides (particularly red hematite and yellow limonite) give the colours white, yellow, light brown, orange and red-brown (black ochre is made from ground charcoal or coal). These photos show the Year 8 students painting with ochres extracted from road cuttings that are crushed, sieved and ground with a mortar and pestle. Water is then added to give the right consistency. Most students follow the Aboriginal tradition of dot painting with sticks but some also used their fingers!
This is a great opportunity to learn from practical experience and to show respect for Aboriginal culture. It is also an engaging way to appreciate a part of the rock cycle.
Colin Price
High School Science Teacher
