This is an alum crystal. Alum is an ingredient in both deodorant and baking powder. It can commonly be found in grocery stores.
I also added a tiny bit of chrome alum - used to tan leather - to dye the crystal purple (regular alum is transparent).
First, I dissolved a mixture of 85g of alum and 5g of chrome alum in 500mL of hot water. Then, as the solution evaporated, small faint purple crystals started to form. I left one of the nicest crystals in the solution, and it slowly got bigger over time. This is what it looks like after 1 month.
If you guys wanna learn more about crystal growing, check out r/crystalgrowing (rabbit hole warning)
I've always liked gemstones, and I find it interesting how these crystals have such smooth faces and sharp edges without being polished. The octahedral shape is also its natural crystal structure. It really looks like a piece of amethyst, one that I grew myself!
Very cool.. I'm a physicist and not a chemist but iirc cyanide can produce a very rich / royal purple hue with the same process (we did that in an 8th grade chemistry class in the 80's .. though we also contaminated the ground water around the same school when we worked with raw mercury - dumping a shitload down the drain.. wait.. I think our science teacher was trying to kill us!)
![image showing [OC] I grew this purple alum crystal at home](2562975c-bcd8-5277-b834-20c760dff0e8.jpg)
crystalchase21 on December 21st, 2025 at 12:34 UTC »
This is an alum crystal. Alum is an ingredient in both deodorant and baking powder. It can commonly be found in grocery stores.
I also added a tiny bit of chrome alum - used to tan leather - to dye the crystal purple (regular alum is transparent).
First, I dissolved a mixture of 85g of alum and 5g of chrome alum in 500mL of hot water. Then, as the solution evaporated, small faint purple crystals started to form. I left one of the nicest crystals in the solution, and it slowly got bigger over time. This is what it looks like after 1 month.
If you guys wanna learn more about crystal growing, check out r/crystalgrowing (rabbit hole warning)
I've always liked gemstones, and I find it interesting how these crystals have such smooth faces and sharp edges without being polished. The octahedral shape is also its natural crystal structure. It really looks like a piece of amethyst, one that I grew myself!
lolxian on December 21st, 2025 at 12:45 UTC »
Your D8 is missing numbers
Ok-Addition1264 on December 21st, 2025 at 12:59 UTC »
Very cool.. I'm a physicist and not a chemist but iirc cyanide can produce a very rich / royal purple hue with the same process (we did that in an 8th grade chemistry class in the 80's .. though we also contaminated the ground water around the same school when we worked with raw mercury - dumping a shitload down the drain.. wait.. I think our science teacher was trying to kill us!)