It is true that if you are deficient in a certain mineral you may have an enhanced ability to taste that mineral, and it will taste good.
Iron
lacking some element or characteristic; defective: deficient in taste.
zinc
Insectivorous plants (flycatcher, sundew and slug catcher, to name only three) can grow in nutrient (mineral) deficient soils because they can catch insects and absorb the insect's nutrients.
Boron itself is not known to have a specific taste as it is a mineral and is not typically consumed in its pure form. However, certain boron compounds may give a bitter taste when ingested in high concentrations.
If we're talking about the American diet, then it's Calcium.
Fluorite is a mineral and should not be tasted as it can be harmful if ingested. It is not recommended to taste or consume any mineral specimens.
There are many different types of malnutrition, but they can be categorized into several main classes. First is caloric malnutrition, in which there is insufficient overall energy in the diet. Second would be protein/carbohydrate/lipid malnutrition, in which one major class of nutrients is deficient. Third would be vitamin/mineral malnutrition, in which one or more vitamins or minerals are deficient. Fourth would be micronutrient malnutrition, in which certain micronutrients are deficient.
calcium
In a cave, you may be able to taste the dampness or mustiness of the air. Additionally, if there are any mineral formations or water sources within the cave, you may be able to taste the mineral content in the water.
Zinc is a mineral that is involved in taste perception. It helps maintain normal taste sensitivity and is important for the function of taste buds on the tongue. Deficiencies in zinc can result in taste disturbances.
She is deficient in Phosphorus. Cows deficient in this mineral eat sand and soil, chew on wood, or even bones from other animals. It might be a good idea to supplement her with phosphorus in her feed or in the mineral mix if other cows like her are showing similar deficiency symptoms.