10. Melting Rocks
 Question
 Does
a rocks melt like an ice cube, all at the
same time?

11. Melting Rocks
 Rocks
melt according to their melting points.
 Example:
 Which
 This
Ice cube with wax
would melt first ice or wax?
example is known as partial melting.
 Partial
Melting: some minerals melt at lower
temperatures and other minerals remain solid
 Think of “stew”

12. Fractional Crystallization
 Opposite
of Partial Melting
 Last to melt are first to solidify (crystallize)

13. Bowen’s Reaction Series
 N.L.
Bowen
 Canadian
 1900’s
 Stated
that “as magma cools, minerals form in
predictable patterns”
 Known as Bowen’s Reaction Series

14. Bowen’s Reaction Series
 Two
Branches
 Feldspars
Continuous,
gradual change of mineral
compositions
 Iron-Rich
An
Minerals
abrupt change of mineral type

15. Bowen’s Reaction Series

17. Feldspars
 Continuous
Change
 First Feldspars are
rich in Calcium (Ca)
 Sodium (Na)
increases as cooling
continues
 Last Feldspars to
form are Sodium rich
(Na)

18. Iron Rich Minerals

Discontinuous Change
 Magnesium (Mg) cools
around 18000C, when
olivine crystallizes, this
continous up to 15570C.
 Now
Pyroxene begins
to form. All olivine that
was formed is now
turned to pyroxene
 Quartz is the last to
form, because silica
and oxygen are the last
to crystallize

19. Why do we find Olivine?

20. •Amongst the common rock forming minerals Felspathoid minerals
containing less % of silica are also present which are usually allied
with Feldspars
Nepheline
(Silicate of sodium
and aluminium=>Albite
Leucite
(Silicate of potassium
and aluminium=>Orthoclase