Download Minerals2 Characteristics - Lincoln Park High School

Minerals
and their
characteristics
Physical Properties of Minerals
• Color: the color a mineral appears to
the eye, under white or natural light.
– Not effective in identifying few
minerals because …
• Some minerals are similar in color.
• Some come in multiple colors.
• Others can have their color
changed.
Physical Properties of Minerals
• LUSTER: the way a mineral reflects light.
–Metallic Luster: shining like polished metal.
(Ex: Pyrite, Galena, Hematite, Magnetite)
–Non-metallic Luster: shining like polished
glass, silk, wax, or any other shiny non-metal.
(Ex: Diamond, Quartz, Opal.)
–There is great variation between metallic and
nonmetallic luster.
–A mineral that does not reflect light is said to
have an “earthy” luster.
Physical Properties of Minerals
• Other acceptable adjectives for luster:
– Adamantine (most lustrous, like diamond)
– Vitreous (glassy)
– Dull (little or very little shine at all)
– Greasy (oily, slick-looking)
– Waxy (like the shine off of a candle)
– Resinous (like tree sap)
– Pearlescent (like a … pearl)
– Adventurine (glittery)
• These terms are often combined (viterous greasy)
Physical Properties of Minerals
• Streak: the color of the powder a mineral
leaves after rubbing it on a “streak plate”.
– More effective than color because the color
of the streak is often different from the
color of the mineral.
– The streak can be more distinct to the
mineral than the color.
Physical Properties of Minerals
• Hardness: a mineral’s resistance to
being scratched.
•Moh’s Hardness Scale: The hardness of
minerals relative to each
other/scratching implements.
– The scale is from 1-10, with 1 being the
softest and 10 being the hardest.
Physical Properties of Minerals
Moh’s
Scale
1
2
3
4
5
6
7
8
9
10
Mineral
Talc
Gypsum
Calcite
Fluorite
Apatite
Feldspar
Quartz
Topaz
Corundum
Diamond
Tools
Fingernail (2.5)
Steel Nail (4.5)
(Avoid the point)
Glass
(5.5)
Streak Plate (5-8)
Physical Properties of Minerals
Cleavage
•the tendency of a mineral to split
along a certain plane or planes.
•not all minerals have cleavage.
•described in numbers of planes and
angles of intersection.
Physical Properties of Minerals
Fracture
•when minerals don’t break
along typical cleavage planes.
•all minerals exhibit fracture.
EXAMPLES:
•Conchoidal: shell-like and
smooth
•Hackly: rough, jagged edges
•Fibrous: breaks into strands
Physical Properties of Minerals
• Other types of fracture:
– Uneven
– Earthy
– Even (smooth)
Novaculite
Novaculite was used by native American Indians (especially in
the southeast) to make arrowheads and other tools. The
fracture and cleavage of this mineral is key to its usefulness.
Special Properties of Minerals
• These are properties that are not present in
all minerals, but are extremely useful in
ID’ing the minerals that have them
• Texture: Having a unique feel to the touch
(talc, graphite)
• Effervesces: Reacts by bubbling when
exposed to acid (calcite, dolomite)
• Taste: What does it taste like?… Duh…
(Halite/Rock Salt)
Special Properties of Minerals
• Smell: What do you think the definition is?
(Sulfur smells like eggs)
• Magnetic: Why would I write anything here?
(Magnetite)
• Density: Basically the amount of water it
displaces. (Crystals with a metallic luster are
generally denser.)
• Phosphorescence: Does it glow under black
light? (Fluorite)