--- title: Gemstones and precious metals — a lesson of Mova's school · trees and pragmatics description: «Gemstones and precious metals», a lesson of the geography course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: A gemstone is a stone people cut and polish because it is beautiful, rare and hard enough to last. --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/geography/51-gemstones-and-precious-metals/) [home](https://md.mova.elamur.ai/free/en/) / [corpora](https://md.mova.elamur.ai/free/en/corpora/) / [school](https://md.mova.elamur.ai/free/en/corpora/school/) / [Geography](https://md.mova.elamur.ai/free/en/corpora/school/geography/) / Gemstones and precious metals # Gemstones and precious metals Lesson 51 of the geography course of Mova's primary school: 21 sentences, each with its syntax tree and pragmatics. The lessons are written for Mova, and their agreed trees are part of Mova corpus 0.4 (CC BY-SA 4.0). How Mova does on its tests: [the lesson at school](https://md.mova.elamur.ai/free/en/school-run/geography/51-gemstones-and-precious-metals/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/geography/51-gemstones-and-precious-metals/0/) — A gemstone is a stone people cut and polish because it is beautiful, rare and hard enough to last. - [1](https://md.mova.elamur.ai/free/en/corpora/school/geography/51-gemstones-and-precious-metals/1/) — Most gems are minerals that grew as crystals deep in the Earth. - [2](https://md.mova.elamur.ai/free/en/corpora/school/geography/51-gemstones-and-precious-metals/2/) — Think of a grandmother's ring with a sparkling diamond. - [3](https://md.mova.elamur.ai/free/en/corpora/school/geography/51-gemstones-and-precious-metals/3/) — That diamond is pure carbon, the same stuff as pencil "lead" and soot, but squeezed so hard about 150 km down in the mantle that its atoms locked into a very hard crystal. - [4](https://md.mova.elamur.ai/free/en/corpora/school/geography/51-gemstones-and-precious-metals/4/) — Diamonds reach us only because rare volcanic pipes once shot them up to the surface fast. - [5](https://md.mova.elamur.ai/free/en/corpora/school/geography/51-gemstones-and-precious-metals/5/) — Rubies and sapphires are one mineral, corundum, and a pinch of another element decides the colour. - [6](https://md.mova.elamur.ai/free/en/corpora/school/geography/51-gemstones-and-precious-metals/6/) — Gold, silver and platinum are precious metals. - [7](https://md.mova.elamur.ai/free/en/corpora/school/geography/51-gemstones-and-precious-metals/7/) — Gold never rusts, so a gold coin from a shipwreck still shines. - [8](https://md.mova.elamur.ai/free/en/corpora/school/geography/51-gemstones-and-precious-metals/8/) — But the story of gems and metals also has a dark side: slaves, forced miners and wars paid for with stones. - [9](https://md.mova.elamur.ai/free/en/corpora/school/geography/51-gemstones-and-precious-metals/9/) — A gemstone is a mineral, or sometimes a material like amber, that is beautiful, rare and hard enough to cut and polish. - [10](https://md.mova.elamur.ai/free/en/corpora/school/geography/51-gemstones-and-precious-metals/10/) — Diamond is pure carbon squeezed deep in the mantle, about 150 km down, and carried up by rare volcanic pipes. - [11](https://md.mova.elamur.ai/free/en/corpora/school/geography/51-gemstones-and-precious-metals/11/) — Until the 1700s almost all the world's diamonds came from India, from the Golconda region. - [12](https://md.mova.elamur.ai/free/en/corpora/school/geography/51-gemstones-and-precious-metals/12/) — Rubies and sapphires are the same mineral, corundum; red corundum is ruby, and other colours are sapphire. - [13](https://md.mova.elamur.ai/free/en/corpora/school/geography/51-gemstones-and-precious-metals/13/) — Tiny traces of other elements, such as chromium in ruby, give corundum its colour. - [14](https://md.mova.elamur.ai/free/en/corpora/school/geography/51-gemstones-and-precious-metals/14/) — Emeralds are green beryl, and the finest came from Colombia, where the Spanish took them from the 1500s. - [15](https://md.mova.elamur.ai/free/en/corpora/school/geography/51-gemstones-and-precious-metals/15/) — Gold does not rust or tarnish and is soft enough to shape, so it has been treasured for thousands of years. - [16](https://md.mova.elamur.ai/free/en/corpora/school/geography/51-gemstones-and-precious-metals/16/) — In the 1300s much of the gold used in Europe and North Africa came from West Africa, traded across the Sahara through the empire of Mali, whose king Mansa Musa became famous for his huge wealth in gold. - [17](https://md.mova.elamur.ai/free/en/corpora/school/geography/51-gemstones-and-precious-metals/17/) — The Spanish forced Indigenous people to mine the silver mountain of Potosí in Bolivia, and many thousands died there. - [18](https://md.mova.elamur.ai/free/en/corpora/school/geography/51-gemstones-and-precious-metals/18/) — Platinum is rarer than gold and is used in car parts called catalytic converters that clean exhaust fumes. - [19](https://md.mova.elamur.ai/free/en/corpora/school/geography/51-gemstones-and-precious-metals/19/) — Some gems are not minerals: amber is fossil tree resin, sometimes with insects trapped inside, and pearls are made by oysters and mussels. - [20](https://md.mova.elamur.ai/free/en/corpora/school/geography/51-gemstones-and-precious-metals/20/) — Diamonds and other gems have paid for wars, so "conflict diamonds" are now meant to be tracked to show where they came from. - ← previous: [Minerals and crystals](https://md.mova.elamur.ai/free/en/corpora/school/geography/50-minerals-and-crystals/) - next →: [Weathering and erosion](https://md.mova.elamur.ai/free/en/corpora/school/geography/52-weathering-and-erosion/) - ↑ back to [Geography](https://md.mova.elamur.ai/free/en/corpora/school/geography/)