sifat fisik mineral - elista:.

PERTEMUAN KE II:
SIFAT FISIK MINERAL
MODUL 2
IDENTIFIKASI MINERAL
Warna
 Bentuk Kristal
 Cerat
 Kilap
 Kekerasan
 Belahan dan Pecahan
 Sifat lain

Warna
Streak (Cerat)

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



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Black - Graphite
Black - Pryite
Black - Magnetite
Black - Chalcopyrite
Gray - Galena
Limonite - Yellowbrown
Hematite - Red-brown
LUSTER (KILAP):
refleksi mineral dalam menangkap sinar:
ada dua yaitu metalik dan non-metalik
Non metalik: kilap kaca, tanah (earthy) dan tidak memantulkan sinar (dull)
Cleavage (Belahan)

Mengikuti
bentuk
kristal
Fracture (Pecahan)


Yaitu bentuk permukaan
antar atom penyusun
mineral saat mineral
pecah atau hancur
Pecahan:



beraturan (regular)
tidak beraturan
(irregular)
Permukaan pecahan:



Kasar (splinterry)
Halus (smooth)
berbentuk kurva
(conchoidal): seperti
gelas saat pecah.
Kekerasan
Crystal Shape
(Bentuk Kristal)
Kubik
 Prismatik
 Tabular
(berlembar)
 Menjarum
 Hexagonal
 Piritohedron

Sifat Lain
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Magnetism - A few minerals are
attracted to a magnet or are themselves
capable of acting as magnets (the most
common magnetic mineral is
magnetite). Because these are so rare,
this property helps narrow the
possibilities drastically when trying to
identify an unknown specimen.
Feel - Some minerals, notably talc and
graphite, feel greasy or slippery when
you rub your fingers over them. The
greasiness occurs because bonds are
so weak in one direction that your finger
pressure alone is enough to break them
and to slide planes of atoms past
neighboring atomic layers
Taste - Geologists use as many
senses as possible in describing and
identifying minerals. Taste is one of the
last tests to be conducted, because
some minerals are poisonous. Some
minerals taste salty-most notably halite
(salt). Sylvite, a mineral similar in all
other properties to halite, tastes bitter.
Taste is thus a diagnostic property
because it distinguishes between
these minerals. NEVER TASTE A
MINERAL UNLESS INSTRUCTED
TO!
Reaction with Dilute Hydrochloric
Acid - This is actually a chemical
property rather than a physical
attribute of a mineral. Minerals
containing the carbonate anion
(C03)2- effervesce ("fizz") when a drop
of dilute hydrochloric acid is placed on
them. Carbon dioxide is liberated from
the mineral and bubbles out through
the acid, creating the fizz. This test is
best performed on powdered minerals.
Calcite (calcium carbonate) will
effervesce readily in either massive or
powdered form, but dolomite (calciummagnesium carbonate) reacts best as
a powder.