Mineral habit and Japanese watermelon
Quick quiz!
What does this...
...have to do with this?
A mineral's habit is the shape that a crystal of that mineral will attain if it gets the chance. When most people hear the word "crystal," the image that comes to mind is of a mineral crystal that has attained its full habit. However, most crystals aren't that pretty. If there aren't enough elemental ingredients, or if there isn't enough time to grow nice and big, or if there are other crystals in the way, then you won't get a nice, sexy crystal. Instead, the mineral crystal's internal structure will fill in whatever space it can, and that will determine its shape. The lower image shows a cartoon of a thin section of rock. In it, you can see a mineral with a "hexagonal" habit, but this actual crystal's shape is jagged and irregular, as dictated by the space available to grow. Most mineral crystals are like this: stunted and "misshapen" as a result of their circumstances.
And that brings us back to the upper image... the square watermelons. As everyone knows, watermelons are approximately ellipsoidal in shape, if given the chance to grow into their full "habit." However, that ellipsoidal shape is tough to cram into a small fridge; it occupies a larger space than its bulk actually takes up. There's a lot of wasted fridge space in the areas adjacent to it. In Japan, a solution has been developed: grow the melons in boxes, so that they are forced to take on a square or rectangular shape. Then, when mature, Japanese consumers can put the square melons in the fridge, confident that no space is being wasted: the melon is taking up almost all of the fridge volume given over to its storage!
Like most minerals, the Japanese watermelons are constrained by their circumstances to grow into shapes that they wouldn't attain on their own.
____________________________
Image sources:
Japanese watermelons - Oddee.com
Thin section cartoon - me, redrawn from a figure in Marshak, 2006.
What does this...
...have to do with this?
A mineral's habit is the shape that a crystal of that mineral will attain if it gets the chance. When most people hear the word "crystal," the image that comes to mind is of a mineral crystal that has attained its full habit. However, most crystals aren't that pretty. If there aren't enough elemental ingredients, or if there isn't enough time to grow nice and big, or if there are other crystals in the way, then you won't get a nice, sexy crystal. Instead, the mineral crystal's internal structure will fill in whatever space it can, and that will determine its shape. The lower image shows a cartoon of a thin section of rock. In it, you can see a mineral with a "hexagonal" habit, but this actual crystal's shape is jagged and irregular, as dictated by the space available to grow. Most mineral crystals are like this: stunted and "misshapen" as a result of their circumstances.
And that brings us back to the upper image... the square watermelons. As everyone knows, watermelons are approximately ellipsoidal in shape, if given the chance to grow into their full "habit." However, that ellipsoidal shape is tough to cram into a small fridge; it occupies a larger space than its bulk actually takes up. There's a lot of wasted fridge space in the areas adjacent to it. In Japan, a solution has been developed: grow the melons in boxes, so that they are forced to take on a square or rectangular shape. Then, when mature, Japanese consumers can put the square melons in the fridge, confident that no space is being wasted: the melon is taking up almost all of the fridge volume given over to its storage!
Like most minerals, the Japanese watermelons are constrained by their circumstances to grow into shapes that they wouldn't attain on their own.
____________________________
Image sources:
Japanese watermelons - Oddee.com
Thin section cartoon - me, redrawn from a figure in Marshak, 2006.
