1. Difference between Mineral and Mineraloid

2. What is Mineral?
Mineral is a naturally occurring, solid, inorganic substance with definite crystal structure and must have a definite chemical composition.
Figure: Mineral (Pyrite and Quartz)

3. What is Mineral? Mineral must have Five properties :
Naturally Occurring - Minerals are found on Earth and not man-made,
Inorganic - Minerals must not consist of living materials,
Solid - Minerals must have a definite shape and volume,
Crystal Structure - Particles inside minerals form a crystal pattern,
Definite Chemical Composition - Minerals are made up of elements from periodic table.

4. What is Mineraloid?
 A mineraloid is a mineral-like substance that does not demonstrate crystallinity. 
Mineraloids possess chemical compositions that vary beyond the generally accepted ranges for specific minerals.
For example, Obsidian is an amorphous glass but  not a crystal.

5. Mineral vs Mineraloid
 A material must meet the following five requirements - naturally occurring, inorganic, solid, ordered atomic structure, definite chemical composition (can vary within a limited range) whereas
A mineraloid is a naturally occurring, inorganic solid that does not exhibit crystallinity.
Moreover, mineral become mineraloid when any of the five properties got missed.

6. Mineral vs Mineraloid
Mineraloid may have the outward appearance of a mineral, but it does not have the “ordered atomic structure” required to meet the definition of a mineral. 
Some mineraloids lack the “definite chemical composition” required to be a mineral.
Minerals are “crystalline.” In other words, they have an ordered atomic structure whereas mineraloids are “amorphous.” This means that their internal atomic structure is not ordered.

7. Mineral vs Mineraloid
For example, Olivine, Pyroxene, Muscovite, Biotite, Calcite and others are the examples of minerals whereas Obsidian is a mineraloid which is a volcanic glass and Pumice, Opal etc. are the mineraloid as well.
Mineraloids can be liquid; Water and mercury are often classified as mineraloids whereas mineral must be a solid.

8. Images of Mineraloid
Figure: Opal
Figure: Water
Figure: Obsidian

9. Images of Minerals

10. References https://geology.com/minerals/mineraloids/
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