Name: __________________________________________________________ Date: __________ Period: _________
Identifying Minerals – Streak, Luster, Cleavage and Fracture
Purpose: To learn how streak, luster, cleavage and fracture help to identify minerals
Materials:
Quartz
Calcite
Obsidian
Pyrite
Feldspar
Hematite
Talc
Galena
Streak plate
Biotite
Chalcopyrite
Muscovite
Sphalerite
Activity 1: Finding Streak of a Mineral
The streak of a mineral is the color of its powder. This is found by rubbing the mineral on an unglazed white porcelain tile
called a streak plate.
1. For each mineral record its color and streak color.
Mineral
Color
Streak
Feldspar
Biotite
Muscovite
Calcite
Talc
Pyrite
Chalcopyrite
Hematite
Galena
Sphalerite
2. Compare the Color and streak columns. Which minerals showed a streak that differed from their color?
3. The first 5 minerals are non-metals. The last five are metals. Can you come up with a general rule that would
describe the streak of each group?
a. Metals - ______________________________________________________ _________________________
_____________________________________________________ _________________________________
b. Non-Metals - ___________________________________________________________________________
_____________________________________________________ _________________________________
Activity 2: Describing Mineral Luster
The luster of a mineral is a way light reflects off of its surface. Use the terms below to describe each mineral sample:
Metallic
Mineral
Nonmetallic (See Figure 1 on page 8)
Luster
Mineral
Feldspar
Pyrite
Biotite
Chalcopyrite
Muscovite
Hematite
Calcite
Galena
Talc
Sphalerite
Luster
Name: __________________________________________________________ Date: __________ Period: _________
Activity 3: How is cleavage in minerals described?
Minerals that split or break along FLAT surfaces have cleavage. A mineral may
have one or more directions of cleavage. How many directions of cleavage do
you see in each of the following? Use the images to the right to help.
Mineral
# of Directions
Mineral
Feldspar
Talc
Biotite
Galena
Muscovite
Sphalerite
# of Directions
Calcite
Activity 4: How is Fracture in Minerals Described
When a mineral breaks along surfaces that are NOT flat, they are sad to have
fracture. Fracture can be defined using the following terms:
Uneven
Splintery
Earthy
Conchoidal
(curved, shell-like)
Fill in the table below using the above words:
Mineral
Fracture
Quartz
Hematite
Splintery
Obsidian
Conchoidal
Earthy
Uneven