Isomorphism

Isomorphic Materials

Isomorphic Materials

Materials that can contain ALTERNATIVE ATOMS within the SAME basic crystal structure

Isomorphic Replacement

• Replacement of 1 chemical element by another in a crystalline material

• crystal structure stays the same but physical properties vary

Isomorphism

minerals exhibit isomorphism when then have identical external forms but differ chemically

4 Isomorphic groups

1. Garnet Group

2. Feldspar Group

3. Olivine Group

4. Tourmaline

2 groups in garnet family

1. Pyralspite

2. Ugrandite

3 garnet species in the Pyralspite Group

1. Pyrope

2. Almandine

3. Spessartine

• "Pyr" = greek for fire!

• Aluminum garnets

3 garnet species in the Ugrandite Group

1. Uvarovite

2. Grossular

3. Andradite

• Calcium garnets!

Pyralspite Group physical properties

• pure red to orange-red colours

• "Pyr" = greek for fire!

• Aluminum garnets (Al as Y element)

Ugrandite Group physical properties

• brown, yellow, green colous

• Calcium garnets! (Ca as X element)

2 Feldspar Families

1. Alkali Feldspar

2. Plagioclase Feldspar

Distinguishing Element in Alkali Feldspar

Potassium (K)

• potassium added into chemical formula of these stones

3 feldspar species in Alkali Feldspar Family

1. Anorthoclase

2. Sanidine/ Orthoclase, Moonstone

3. Microline Amazonite

6 feldspar species in Plagioclase Feldspar Family

1. Albite

2. Oligoclase

3. Andesine

4. Labradorite

5. Bytownite

6. Anorthite

2 species in Olivine Group

1. Forsterite

2. Fayalite