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1. Put Safety Quiz, Safety Contract, and DonorsChoose form (if applicable) in front of you. I will check them off. 2. Catalyst Question: Based on the four characteristics of minerals, how do you think geologists identify different minerals?
Catalyst Announcements Mini-Lesson: Identifying Minerals Lab: Geologist for a Day Alternative: Mineral Packet Work Time (Foldables) Closing Exit Ticket
Be sure that by the end of class on Thursday (10/25) you have completed your foldable on silicates, carbonates, and oxides. I will be collecting/marking them. Only marked foldables may be used on the quiz. If you were absent, see me during work time.
Up to 90% credit today Be sure to stay up-to-date!
By the end of class, CWBAT create a lab procedure to determine the identities of unknown minerals. CCSS Reading Grades ▪ Follow precisely a complex multistep procedure when carrying out experiments, taking measurements, or performing technical tasks; analyze the specific results based on explanations in the text. CRS Scientific Investigation: ▪ Determine the hypothesis for an experiment. Assessments: ▪ Assessed in creation of lab procedure/completion of packet.
More than 3000 minerals in Earth’s crust How do you identify so many? Use a combination of tests!
1. Color 2. Luster 3. Texture 4. Streak 5. Hardness 6. Cleavage/Fracture 7. Density/Specific Gravity 8. Special Properties
Most noticeable characteristic Can be due to the presence of trace elements Quartz types ▪ Rose quartz (pink) contains manganese or titanium ▪ Jasper (red) contains iron oxides ▪ Amethyst (purple) contains ferric iron ▪ Citrine (orange) contains iron hydrates All of these are quartz! The least reliable way to identify a mineral These all have the same chemical composition, they just contain different trace elements!
The way a mineral reflects light from its surface. Described as either Metallic Nonmetallic
METALLIC Shiny; reflects like chrome on a car Examples: Copper, silver, gold, galena NONMETALLIC Not shiny; described as dull, pearly, waxy, or silky Examples: Calcite, gypsum, sulfur, quartz
How a mineral feels to the touch Descriptions: Smooth Rough Ragged Greasy Soapy Glassy
The color of a mineral when it is broken up and powdered. Determine by rubbing across an unglazed porcelain plate Will not always be the same as the external color!
Measure of how easily a mineral can be scratched Mohs Scale of Hardness Based on known hardness of 10 minerals ▪ 1: Talc (scratched by fingernail) ▪ 10: Diamond (scratches all common objects) One of the most useful tests
copper coin the side of a steel nail Leaves mark on a streak plate
How minerals break is determined by atomic arrangement. Minerals split along planes where atomic bonding is relatively weak.
Cleavage A mineral has cleavage when it splits relatively easily and evenly along one or more flat planes. Examples: ▪ Mica ▪ Perfect cleavage in one direction ▪ Halite ▪ Cubic cleavage (breaks in 3 directions)
Fracture When minerals break with rough or jagged edges Examples: ▪ Quartz ▪ Uneven breaks along jagged edges due to tightly bonded atoms* ▪ Rock obsidian ▪ Conchoidal fractures (arc- like patterns resembling clam shells)
When you lift two equally-sized minerals and one feels heavier. Density D = M/V Reflects atomic weight and structure of a mineral Specific Gravity More accurate than estimates of density S.G.= weight of substance/weight of equal volume of water at 4 ° C
Double refraction Causes 1 ray of light to bend in 2 directions Calcite, Iceland spar Reaction with HCl Reaction creates bubbles of CO2 Calcite (calcium carbonate) Magnetism Acts like a magnet Magnetite, lodestone Odor Rotten egg smell Sphalerite, sulfur Volunteer needed!
Contacts out Hair tied back Absolutely NO Gum Food Drinks (even water!) If you did not turn in your forms, gather near the whiteboard for further instructions.
1. Read pages Silently/independently 2. Groups of three 1) Supervisor ▪ Gathers materials/responsible for directions being followed ▪ Leads group through experiments 2) Data Manager ▪ Create chart/write 3) Primary Experimenter ▪ Carry out tests ▪ Acid, nail, etc.
On sheet in basket: Magnifying glass (x1) Add “Paper clip (x1)
Answer Questions: Plan the Experiment ▪ #1, 3, 4 Analyze ▪ #1-4 Make sure that you have a hypothesis, chart, and write-up of the questions. When finished, raise your hand.
Use pages 81-83
By the end of class, CWBAT create a lab procedure to determine the identities of unknown minerals.
On the back of your Catalyst sheet… What are the most reliable ways to determine the identity of a mineral sample? What are the least reliable ways?