Tourmaline is the only major silicate mineral that contains structural boron.
Because it is highly resistant to weathering, boron deficiency is common in sandy, highly leached soils where tourmaline breaks down very slowly.
Step 1: Understanding the Concept:
Plants absorb essential plant nutrients from soil mineral reserves as these minerals weather and break down over time.
Boron is an essential micronutrient required for cell wall synthesis, pollen tube germination, and sugar translocation. Step 2: Detailed Explanation:
Let us analyze the chemical composition of each mineral listed in the options:
- Tourmaline: This is a complex crystalline silicate mineral containing boron, aluminum, iron, magnesium, sodium, lithium, or potassium.
The generalized chemical formula of tourmaline is \(\text{Na(Mg,Fe,Li,Al)}_3\text{Al}_6\text{Si}_6\text{O}_{18}(\text{BO}_3)_3(\text{OH})_4\).
It contains approximately \(3\%\text{ to }4\%\) boron by weight.
Tourmaline is highly resistant to weathering, meaning that boron is released very slowly into the soil solution, making it the primary mineral source of boron in soils.
- Topaz: This is a silicate mineral of aluminum and fluorine with the chemical formula \(\text{Al}_2\text{SiO}_4(\text{F,OH})_2\), containing no boron.
- Epidote: This is a calcium aluminum iron silicate mineral, containing no boron.
- Francolite: This is a carbonate-rich variety of fluorapatite, which serves as a source of phosphorus, containing no boron.
Therefore, the mineral containing boron is tourmaline. Step 2: Final Answer:
The mineral containing boron (B) is tourmaline.
