Suggested teacher's guide for discussion for grade 7 science

1. MA. RACHEL B. ESPINO
Buhatan National High School
Purok Marcos, Buhatan, Sorsogon City

2.  A mineral is a natural inorganic substances
with a definite chemical composition. It is
found in the earth’s crust and does not come
from living things. It is a naturally formed
solid element or compound in which atoms
and molecules are bound in together in a
definite orderly arrangement to form
crystals. Most of these crystals are too small
to be seen even under a microscope. But
some crystals are big enough to be
identified.

3.  Minerals are found in rocks. They appear like
grains set firmly in a bed of rock. Some are
dark and others are light in color. A rock may
be composed of only one kind of mineral
such as pure limestone, which is composed of
calcite. Others may have more than one
mineral like granite which has 3 very
common minerals – quartz, feldspar and
mica.

5.  Minerals are most easily identified by their
physical properties. These are:
1. Hardness
2. Color
3. Streak
4. Luster
5. Cleavage and Fracture

6.  Hardness is the resistance of a mineral to
scratching or abrasion. To test the hardness
of a mineral sample, scratch it against
another. That which can scratch by the other
is softer.

7.  Diamond is the hardest known mineral and is
industrially used to cut or bore holes into
glass, stone and other hard metals. Talc is
the softest mineral used especially in making
talcum powder.

8.  Color is one way of telling
one mineral from
another. It is their usually
most noticeable and
interesting property. But
it is not the most
reliable. The outside
color of the mineral may
have been changed by the
atmosphere; hence, it is
safe to examine the color
of a fresh surface by
breaking it apart.

9.  A mineral may be translucent like mica,
white or pink like quartz or lead gray like
galena. Hematite is dark red while sulfur is
yellow, while silver, tin and magnesium have
almost the same gray-white color.
MICA QUARTZ GALENA
HEMATITE
SULFUR
SILVER

10.  Streak refers to the
color of the powder
a rock or mineral
leaves behind when
rubbed on a rough
surface. The streak
test consist of
rubbing the mineral
against a hard
surface.

11.  However, the color of the streak is not
always the same as the color of the mineral.
For example, the mineral pyrite which has
the same color as gold leaves a greenish-
black streak while gold always leaves a gold
streak.
PYRITE
GOLD

12.  The mineral hematite may be reddish brown
or brownish black when viewed in solid form
but is always cherry red in powder form, that
is why hematite is also called bloodstone.

13.  Luster is the appearance of the surface of a
mineral in reflected light. A mineral that can
reflect much light appears very shiny. Metals
have metallic luster like silver and gold.
Nonmetals are dull such as quartz, mica or
asbestos.

14.  Cleavage and fracture
describe the way a mineral
breaks. Any irregular break
is termed a fracture while
the tendency of a certain
minerals to break along
one or more planes when
put under pressure is
called cleavage. Minerals
split horizontally into thin
sheets. Feldspar splits at
nearly right angles in
different directions.

15. FELDSPAR COPPER
SULFUR
SALT

16.  The richness of the Philippines in terms of
mineral resources is being attributed to its
location at the western fringes of so called
Pacific Ring of Fire – a ground found to be
superloaded with mineral deposits. Globally,
we are rankes 5th as most mineralized
country in the world.

18.  The Philippines is situated along the circum
Pacific Ring of Fire where the processes of
volcanism and plate convergence caused the
deposition of minerals, both metallic and
non-metallic. In fact, the large reserves of
various kind of minerals beneath our ground
has put the country in the world mineral map
as 5th mineral country in the world, 3rd in
gold reserves, 4th in copper and 5th in nickel.

20.  Around 9 million hectares or 30% of the
country’s total land area of 30 million
hectares are believed to contain important
metallic mineral deposits; while 5 million are
also known to be potential site for
nonmetallic reserves.

21.  Among our important metallic minerals found
in abundance in various parts of the country
include gold, copper, iron, chromite, nickel,
cobalt and platinum while our non-metallic
resources include sand and gravel,
limestone, marble, clay and other quarry
materials.

22.  The most prolific copper and gold products
are found in Baguio and Mankayan district
province of Benguet; although the Surigao-
Davao district are also contributing much to
Philippine gold production. Major producers
of nickel are in Palawan and Surigao.

27.  Science Grade 7 Learners Module
 Integrated Science I Textbook
 Salandanan, Gloria G. Earth Science, Quezon
City: Phoenix Publishing House, 1988.
 http://www.philippinestamps.net/RP2009-
Minerals.htm
 http://www.denr.gov.ph/news-and-
features/latest-news/16-mineral-
resources.html
 http://nap.psa.gov.ph/peenra/results/miner
al/default.asp