Chapter 5: minerals
Mineralogists: people who identif ineerals, ineerals ake up ost erocks and sedi ents oi the
solid eaerth
5.2 what is a mineral?
A naturally occurring(1) solid(2) , formed by geologic processes(3) that has a crystalline structure(4)
and a definable chemical composiion(5). Al ost all aere inorganic(6).
1) ioer ed in natuere. Nagebootste aere called “sfnthetc ineeralss
(2) aintains shape, no infuence oi its containeer. Liquid is neveer a ineeral
(3)
o teraditonallf -> eresult oi solidiicaton oi olten erock/dierect perecipitaton iero wateer
soluton. No oerganis s.
o Now -> solid, cerfstalline ateerials ioer ed bf oerganis s -> biogenic ineerals.
(4) ato s iied in pateern oerdeerlf -> cerfstalline solid. .ateern itseli = cerfstal latce
(5) possible to werite a che ical ioer ula
(6) oerganic consists C-C / C-H. ioer in living oerganis s / have that steructuere.
Glass is not a ineeral is not a cerfstalline
5.3 Crystals and their structure
What is a crystal?
Crystal: single, contnuous piece oi a cerfstalline solid, tfpicallf bounded bf fat sueriaces (crystal
faces) that gerow natuerallf as the ineerals ioer .
The angle between two adjacent cerfstal iaces oi one speci en is identcal to the angle oi the
coereresponding iaces oi anotheer speci en. it is consistent in a paertculaer ineeral.
Looking inside a mineral
Diffraction: The splitng oi light into anf tnf bea s that inteerieere with one anotheer.
Foer a cerfstal to cause this the ato s ust be eregulaer spaced and the spacing ust be co paerable to
the wavelength oi X-erafs. The leaerned how to use X-eraf diferacton pateerns as a basis ioer deining
speciic aererange ent oi ato s in cerfstals. This aererange ent deines the crystal structure oi a
ineeral.
In cerfstals the pateern is deined bf the eregulaer spacing oi ele ents, bf 2+ ato s bf the eregulaer
alteernaton oi ato s. The pateern af conterol the shape. Because oi the pateern oi ato s, the
steructuere has sf eterf. We can ereconsteruct this bf using a clusteer oi balls.
The waf ato s oer ions it togetheer in a cerfstal steructuere, is difeerent in difeerent ineerals. Anions (-
ionen) tend to be biggeer than catons (+ionen, less electerons). In ineerals with ionic bonding catons
tend to be suererounded bf anions. A vaerietf oi packing can occuer.
So can be aereranged in oere than one waf: polymorphs: aere 2 oer oere difeerent ineerals that have
the sa e che ical co positon but difeerent cerfstal steructueres.
The formation and destruction of minerals
Five wafs to ioer a new ineeral cerfstal
1) Bf the solidiicaton oi a elt, eaning the iereezing oi a liquid.
Mineralogists: people who identif ineerals, ineerals ake up ost erocks and sedi ents oi the
solid eaerth
5.2 what is a mineral?
A naturally occurring(1) solid(2) , formed by geologic processes(3) that has a crystalline structure(4)
and a definable chemical composiion(5). Al ost all aere inorganic(6).
1) ioer ed in natuere. Nagebootste aere called “sfnthetc ineeralss
(2) aintains shape, no infuence oi its containeer. Liquid is neveer a ineeral
(3)
o teraditonallf -> eresult oi solidiicaton oi olten erock/dierect perecipitaton iero wateer
soluton. No oerganis s.
o Now -> solid, cerfstalline ateerials ioer ed bf oerganis s -> biogenic ineerals.
(4) ato s iied in pateern oerdeerlf -> cerfstalline solid. .ateern itseli = cerfstal latce
(5) possible to werite a che ical ioer ula
(6) oerganic consists C-C / C-H. ioer in living oerganis s / have that steructuere.
Glass is not a ineeral is not a cerfstalline
5.3 Crystals and their structure
What is a crystal?
Crystal: single, contnuous piece oi a cerfstalline solid, tfpicallf bounded bf fat sueriaces (crystal
faces) that gerow natuerallf as the ineerals ioer .
The angle between two adjacent cerfstal iaces oi one speci en is identcal to the angle oi the
coereresponding iaces oi anotheer speci en. it is consistent in a paertculaer ineeral.
Looking inside a mineral
Diffraction: The splitng oi light into anf tnf bea s that inteerieere with one anotheer.
Foer a cerfstal to cause this the ato s ust be eregulaer spaced and the spacing ust be co paerable to
the wavelength oi X-erafs. The leaerned how to use X-eraf diferacton pateerns as a basis ioer deining
speciic aererange ent oi ato s in cerfstals. This aererange ent deines the crystal structure oi a
ineeral.
In cerfstals the pateern is deined bf the eregulaer spacing oi ele ents, bf 2+ ato s bf the eregulaer
alteernaton oi ato s. The pateern af conterol the shape. Because oi the pateern oi ato s, the
steructuere has sf eterf. We can ereconsteruct this bf using a clusteer oi balls.
The waf ato s oer ions it togetheer in a cerfstal steructuere, is difeerent in difeerent ineerals. Anions (-
ionen) tend to be biggeer than catons (+ionen, less electerons). In ineerals with ionic bonding catons
tend to be suererounded bf anions. A vaerietf oi packing can occuer.
So can be aereranged in oere than one waf: polymorphs: aere 2 oer oere difeerent ineerals that have
the sa e che ical co positon but difeerent cerfstal steructueres.
The formation and destruction of minerals
Five wafs to ioer a new ineeral cerfstal
1) Bf the solidiicaton oi a elt, eaning the iereezing oi a liquid.
