======Making Light by Rubbing Quartz======


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**Materials: **{{$demo.materials_description}}\\
**Difficulty: **{{$demo.difficulty_description}}\\
**Safety: **{{$demo.safety_description}}\\
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**Categories:** {{$demo.categories}}
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**Alternative titles:** Real Glowing Rocks, Triboluminescence
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====Summary====                   
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====Procedure====  
  - Collect two clean, dry pieces of clear quartz large enough to hold comfortably. Inspect for sharp edges and brush off any grit.
  - Darken the room completely and allow your eyes to adapt for 1 to 2 minutes.
  - Hold one quartz in each hand with the flattest faces facing each other.
  - Press the faces together firmly and rub or slide with moderate pressure. Alternatively, tap the pieces together gently, edge to face.
  - Watch for short, blue white sparks and glows at the contact point. Note any faint sharp smell in the air near the stones.



====Links==== 
Making Cold Light From Crystals - The Action Lab: 
{{youtube>kqCR2YZQtBQ?}}\\

The Discovery of Crystal Light! | Triboluminescence - Plasma Channel: 
{{youtube>Dv36mGUMjdM?}}\\

📄 Real Glowing Rocks - Science Fun For Everyone: [[https://www.sciencefun.org/kidszone/experiments/real-glowing-rocks/]]\\


====Variations====
  * Compare quartz types: clear rock crystal vs milky quartz vs smoky quartz.
  * Chill one sample in a refrigerator or warm it slightly in your hands, then repeat to test temperature effects..
  * Test humidity: perform on a dry day vs a humid day to see if moisture reduces the effect.



====Safety Precautions====
  * Wear safety glasses to protect against chips or shards. Do not strike hard enough to shatter the quartz.
  * Inspect and smooth sharp edges if needed. Handle fragments with care and avoid creating dust.
  * Work over a tray or soft cloth so dropped stones do not crack or bounce.
  * Keep fingers clear of pinch points when rubbing stones together.
  * If you try sugar or candy, keep fragments out of eyes and do not chew very hard candies if that poses a dental risk.




====Questions to Consider====
  * What produces the light when you rub quartz? (Mechanical stress separates charges in the crystal; rapid recombination creates tiny electrical discharges that excite air molecules, which emit light.)
  * Why is the glow bluish white? (Excited nitrogen and oxygen in air emit mainly in the blue ultraviolet region, which appears bluish to our eyes.)
  * Why might clear quartz glow more than cloudy quartz? (Fewer impurities and less internal scattering let more of the light escape to your eyes.)
  * What causes the smell during the demo? (Small electrical discharges can generate ozone and other reactive oxygen species, giving a sharp odor.)
  * How would humidity change the effect? (Moist air and surface films conduct away charge, reducing the voltage build up and dimming the glow.)