d-Menthol vs dl-menthol: Does an enantiomer and its racemic mixture have different melting points? I am checking out Wikipedia and it shows a different melting point (m.p.) for l-menthol $(\pu{42 ^\circ C}$ to $\pu{45 ^\circ C})$ vs dl-menthol $(\pu{36 ^\circ C}$ to $\pu{38 ^\circ C}).$ 

How is this possible? d-menthol and l-menthol being enantiomers, shouldn't they have identical physical properties including the m.p.? 


  The two enantiomers of a molecule possess the same physical properties (e.g., melting point, boiling point, polarity etc.) and so behave identically to each other.


If so, why would the racemic mixture have any different m.p.? I.e. you can't just physically  mix two pure materials with the same m.p. and end up with a material with a different m.p., right?

I checked out Common Fragrance and Flavor Materials by Surburg and Panten [1, p. 55] just to be sure and the data agrees. The m.p. of the d-menthol and dl-menthol again seem to be different:


  Other physical constants of commercially available levorotatory and racemic
  menthols are: (−)-menthol [2216-51-5], mp $\pu{43 °C},$ $n_\mathrm{D}^{20}~1.4600,$ $[α]_\mathrm{D}^{20}~–50^\circ;$ (±)-
  menthol [15356-70-4], mp $\pu{38 °C},$ $n_\mathrm{D}^{20}~1.4615.$


References


Surburg, H.; Panten, J. Common Fragrance and Flavor Materials: Preparation, Properties and Uses, 5th, Completely Revised and Enlarged edition; Wiley-VCH: Weinheim, 2006. ISBN 978-3-527-31315-0.
If solid menthol were just amorphous, then you would expect the racemate and each enantiomer to exhibit identical melting points. However, if you read further on the Wikipedia page you reference, you'll see that racemic vs. enantiopure menthol crystallizes differently:


  The two crystal forms for racemic menthol have melting points of 28 °C and 38 °C. Pure (−)-menthol has four crystal forms, of which the most stable is the α form, the familiar broad needles.


(This information is trustworthy and corroborated in the primary literature; here is one example)

The melting point of a crystalline solid has to do with how well the molecules can pack together. In other words, on a molecular level, there is an orientation dependence. The better the molecular packing, the stronger the intermolecular forces, and the higher the melting point - since it takes more energy to separate the molecules. This is why the enantiopure menthol has a higher melting point.