Friday, June 18, 2010
I remember being a little girl and seeing my father's collection of cut stones inside little plexiglass boxes, all carefully arranged in black boxes with lids, stacked inside the safe. It was kind of magical, like a treasure hidden in the safe. I would see a row of colorful stones and ask: What's this one? He would reply: Tourmaline. And this? Tourmaline. This? Tourmaline. It would go on for rows and rows. It was my favorite. How can they come in so many different colors?
There are many factors that influence color in minerals. My favorite "factor" is impurity.
Impurities are elements (e.g., Ti, V, Cr, Mn, Fe, Co, Ni, Cu...) that are not present in the pure compound. They occur in low concentration in the stone.
Take Amethyst, Citrine, Rose Quartz, Smoky Quartz. They all have the same SiO2 Quartz formula. What causes the different colors is the presence of chemical impurities.
Beryl is another example. With different impurities, we get different colors:
Morganite and Red Beryl contain Manganese. Aquamarine and Heliodor are colored by Iron. Emerald is colored by Cromium. The hues depend on the amounts of each element.
One famous example of color by impurity is Paraiba Tourmaline. The bright neon color is cause by Copper.
Another interesting fact is that Chromium makes Emerald green, but it also makes Ruby red.
Here are some examples of color by impurity:
Middle row: Tourmalines: Rubellite, Yellow and Green
Bottom row: Beryls: Aquamarine, Morganite and Heliodor
I still marvel when I see a Tourmaline in a color that I haven't seen before!
Thursday, June 10, 2010
After getting disappointed with my last gnocchi order, I decided I could do better. I even had the sauce in mind. I just had to do the dumplings.. "Just".. as if it was that simple.
I got beautiful yukon gold potatoes. Big, with not a lot of bumps and smooth skin. I usually bake them in the oven or the microwave. I Find that if you boil them, the water makes it too soggy for gnocchi, calling for more flour. Since the potatoes I got were huge, it took half an hour for them to bake. So, let's start with the recipe:
3 pounds of yukon gold (russet works too)
1 and a half cup of flour
1 large egg
1 teaspoon of kosher salt
1/2 cup of olive oil or any mild vegetable oil.
A big pot with boiling water with 1 tbs of salt.
After the potatoes are baked, press them through a potato ricer. (Yes, it is one more gadget to buy but, you can use them for fantastic mashed potatoes too)
Make a little potato "volcano" on the clean surface of your counter.
Sprinkle the whole volcano with the flour and the salt and break the egg in the center.
Start mixing everything with a fork, and then begin kneading with your hands until it come together. If it is still sticky, add more flour and keep kneading until it's dry to the touch. Divide the dough into 6 balls. Roll the balls into ropes of 3/4 inch diameter, and cut them in little pillows of 1 inch.
It is very easy to make this recipe. The only problem is that it's time consuming and can be messy. So messy that afterwards I thought it would take forever for me to want to venture in gnocchi-land again. I must confess, it was so good, I am already flirting with the idea of doing it again soon. Who knows? maybe with the experience I got, it will only take me 2 hours.
The unused gnocchi that was kept in the fridge can be revived by a quick boil again, or pan sauted with olive oil and then served with he same sauce or a different one. hmm I am having new ideas...