You're likely thinking of the Provo City Center Temple, which does have a unique, dark spire. This design choice isn't common for Mormon temples or meetinghouses.
Here's why the Provo City Center Temple has a dark spire:
* Historical Preservation: The temple was built within the historic Provo Tabernacle, which was gutted by fire in 2010. The exterior walls were preserved, and the design team sought to honor the building's history while creating a sacred space.
* Contrast and Symbolism: The dark spire contrasts with the lighter exterior of the building and the surrounding area. The contrast draws the eye upwards, symbolizing a connection to heaven and the importance of spiritual pursuits. The dark color might also evoke a sense of reverence and history, connecting the temple to the past.
It's important to note that the Provo City Center Temple's design is unique, and the dark spire isn't a standard feature of Mormon temples or meetinghouses. Other factors may have influenced this design choice, but the ones listed above are generally accepted as the main reasons.